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<title>Life Lexicon (S)</title>
<meta name="author" content="Stephen A. Silver">
<meta name="description" content="Part of Stephen Silver's Life Lexicon.">
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<center><A HREF="lex.htm">Introduction</A> | <A HREF="lex_bib.htm">Bibliography</A></center></center>
<hr>
<center>
<b>
<A HREF="lex_1.htm">1-9</A> |
<A HREF="lex_a.htm">A</A> |
<A HREF="lex_b.htm">B</A> |
<A HREF="lex_c.htm">C</A> |
<A HREF="lex_d.htm">D</A> |
<A HREF="lex_e.htm">E</A> |
<A HREF="lex_f.htm">F</A> |
<A HREF="lex_g.htm">G</A> |
<A HREF="lex_h.htm">H</A> |
<A HREF="lex_i.htm">I</A> |
<A HREF="lex_j.htm">J</A> |
<A HREF="lex_k.htm">K</A> |
<A HREF="lex_l.htm">L</A> |
<A HREF="lex_m.htm">M</A> |
<A HREF="lex_n.htm">N</A> |
<A HREF="lex_o.htm">O</A> |
<A HREF="lex_p.htm">P</A> |
<A HREF="lex_q.htm">Q</A> |
<A HREF="lex_r.htm">R</A> |
<A HREF="lex_s.htm">S</A> |
<A HREF="lex_t.htm">T</A> |
<A HREF="lex_u.htm">U</A> |
<A HREF="lex_v.htm">V</A> |
<A HREF="lex_w.htm">W</A> |
<A HREF="lex_x.htm">X</A> |
<A HREF="lex_y.htm">Y</A> |
<A href="lex_z.htm">Z</A></b>

</center>
<hr>
<p><a name=s>:</a><b>S</b> Usually means <a href="lex_b.htm#bigs">big S</a>, but may sometimes mean <a href="lex_p.htm#paperclip">paperclip</a>.
<p><a name=sailboat>:</a><b>sailboat</b> (p16) A <a href="lex_b.htm#boat">boat</a> <a href="lex_h.htm#hassle">hassled</a> by a <a href="lex_k.htm#koksgalaxy">Kok's galaxy</a>, a <a href="lex_f.htm#figure8">figure-8</a>
and two <a href="lex_e.htm#eater3">eater3s</a>. Found by Robert Wainwright in June 1984.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:........O...........O........$.......O.O.........O.O.......$........O...........O........$.............................$......OOOOO.......OOOOO......$.....O....O.......O....O.....$....O..O.............O..O....$.O..O.OO.............OO.O..O.$O.O.O.....O.......O.....O.O.O$.O..O....O.O.....O.O....O..O.$....OO..O..O.....O..O..OO....$.........OO.......OO.........$.............OO..............$.............O.O.............$........O..O..O..............$.......O.....................$.....OO..........OOO.........$..O......OO.O....OOO.........$.....O...O..O....OOO.........$.....OOO.O...O......OOO......$..O...........O.....OOO......$...O...O.OOO........OOO......$....O..O...O.................$....O.OO......O..............$..........OO.................$.........O...................$.....O..O....................$"
>........O...........O........
.......O.O.........O.O.......
........O...........O........
.............................
......OOOOO.......OOOOO......
.....O....O.......O....O.....
....O..O.............O..O....
.O..O.OO.............OO.O..O.
O.O.O.....O.......O.....O.O.O
.O..O....O.O.....O.O....O..O.
....OO..O..O.....O..O..OO....
.........OO.......OO.........
.............OO..............
.............O.O.............
........O..O..O..............
.......O.....................
.....OO..........OOO.........
..O......OO.O....OOO.........
.....O...O..O....OOO.........
.....OOO.O...O......OOO......
..O...........O.....OOO......
...O...O.OOO........OOO......
....O..O...O.................
....O.OO......O..............
..........OO.................
.........O...................
.....O..O....................
</a></pre></td></tr></table></center>
<p><a name=salvo>:</a><b>salvo</b> A collection of spaceships, usually gliders, all travelling in
the same direction. Any valid glider construction <a href="lex_r.htm#recipe">recipe</a> can be
partitioned into no more than four salvos. Compare <a href="lex_f.htm#flotilla">flotilla</a>. In
contrast with a <a href="lex_c.htm#convoy">convoy</a>, the spaceships in a salvo are usually
consumed by the reactions that they cause. Simple examples include
<a href="lex_b.htm#blockpusher">block pusher</a> and <a href="lex_b.htm#blockpull">block pull</a>.
<p>Salvos may be <a href="#slow">slow</a> or <a href="#synchronized">synchronized</a>. The following partially
<a href="#synchronized">synchronized</a> three-glider salvo produces an <a href="lex_l.htm#lwss">LWSS</a> from a block.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO........$OO........$..........$..........$OOO.......$O.........$.O........$..........$.......OOO$.......O..$........O.$..........$..........$..........$..........$..........$..........$.......OOO$.......O..$........O.$"
>OO........
OO........
..........
..........
OOO.......
O.........
.O........
..........
.......OOO
.......O..
........O.
..........
..........
..........
..........
..........
..........
.......OOO
.......O..
........O.
</a></pre></td></tr></table></center>
The above is a synchronized salvo and not a slow salvo, because the
second glider must follow the first with the exact separation shown.
The third glider can be considered to be a slow glider, because it
will still delete the temporary loaf no matter how many <a href="lex_t.htm#tick">ticks</a> it is
delayed. The <a href="#slowgliderconstruction">slow glider construction</a> entry includes an example of
a true slow salvo.
<p><a name=sawtooth>:</a><b>sawtooth</b> Any finite pattern whose <a href="lex_p.htm#population">population</a> grows without bound
but does not tend to infinity. (In other words, the population
reaches new heights infinitely often, but also infinitely often
returns to some fixed value.) Conway's preferred plural is
"sawteeth".
<p>The first sawtooth was constructed by Dean Hickerson in April 1991.
The current smallest known sawtooth was found by a conwaylife.com
forum user with the online handle 'thunk'. It has a bounding box of
74x60, and is the smallest known sawtooth in terms of its minimum
repeating population of 177 cells. The following variant has a higher
repeating population of 194 and an optimized bounding box of 62x56:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.....................................................OO.O.....$.....................................................O.OO.....$..............................................................$...........OO.................................................$...........OO.................................................$..............................................................$..............................................................$..............OO............................OO.......OO.....OO$....OO........OO.....................................OO.....OO$.....O.....................................O.O................$....O......OO............................O..............OO....$....OO.....OO........................OO.O.OO............OO....$......................................O.OO....................$.......................................O......................$..............................................................$.................................OO...........................$.................................OO...........................$..............................................................$.............................OO.....OO........................$.............................OO.....OO........................$..............................................................$..............................................................$..............................................................$.....................OOO......................................$.....................O..O.....................................$.....................O.OO.....................................$..............................................................$..............................................................$..............................................................$....................OO............O.........O.................$....................O..O..........O.O.....OOO.................$..OOOO...............OOO..........OO.....O....................$OO....OO.................................OO...................$OO.....O......................................................$..OO.O.O..............OO......................................$.......O..............OO......................................$...O...O..........................O....O......................$...O....O.......................OO.....O......................$.....OOO...O.....................OO...O.O.....................$.....OO....O.........................OO.OO....................$...........OO.......................O.....O...................$.............O.........................O......................$.............OOO....................OO...OO...................$..............................................................$..............................................................$................O.....................O.......................$...............O.OOOOO................O.......................$..............OO.....O...............O........................$..............OO...O..O.......................................$......................O.......................................$................OO.O..O................OO.....................$...................O..O................OO.....................$....................OO........................................$....................OO.....O....O.............................$.........................OO.OOOO.OO...........................$...........................O....O.............................$"
>.....................................................OO.O.....
.....................................................O.OO.....
..............................................................
...........OO.................................................
...........OO.................................................
..............................................................
..............................................................
..............OO............................OO.......OO.....OO
....OO........OO.....................................OO.....OO
.....O.....................................O.O................
....O......OO............................O..............OO....
....OO.....OO........................OO.O.OO............OO....
......................................O.OO....................
.......................................O......................
..............................................................
.................................OO...........................
.................................OO...........................
..............................................................
.............................OO.....OO........................
.............................OO.....OO........................
..............................................................
..............................................................
..............................................................
.....................OOO......................................
.....................O..O.....................................
.....................O.OO.....................................
..............................................................
..............................................................
..............................................................
....................OO............O.........O.................
....................O..O..........O.O.....OOO.................
..OOOO...............OOO..........OO.....O....................
OO....OO.................................OO...................
OO.....O......................................................
..OO.O.O..............OO......................................
.......O..............OO......................................
...O...O..........................O....O......................
...O....O.......................OO.....O......................
.....OOO...O.....................OO...O.O.....................
.....OO....O.........................OO.OO....................
...........OO.......................O.....O...................
.............O.........................O......................
.............OOO....................OO...OO...................
..............................................................
..............................................................
................O.....................O.......................
...............O.OOOOO................O.......................
..............OO.....O...............O........................
..............OO...O..O.......................................
......................O.......................................
................OO.O..O................OO.....................
...................O..O................OO.....................
....................OO........................................
....................OO.....O....O.............................
.........................OO.OOOO.OO...........................
...........................O....O.............................
</a></pre></td></tr></table></center>
Patterns combining a fast <a href="lex_p.htm#puffer">puffer</a> with a slower <a href="#spaceship">spaceship</a> have
also been constructed (see <a href="lex_m.htm#movingsawtooth">moving sawtooth</a>). See also
<a href="lex_t.htm#tractorbeam">tractor beam</a>.
<p><a name=sbm>:</a><b>SBM</b> = <a href="#slidingblockmemory">sliding block memory</a>
<p><a name=schickengine>:</a><b>Schick engine</b> (<i>c</i>/2 orthogonally, p12) This <a href="#spaceship">spaceship</a>, found by Paul
Schick in 1972, produces a large <a href="#spark">spark</a> (the 15 live cells at the
rear in the <a href="lex_p.htm#phase">phase</a> shown below) which can be <a href="lex_p.htm#perturb">perturbed</a> by other
<i>c</i>/2 spaceships to form a variety of <a href="lex_p.htm#puffer">puffers</a>. See <a href="lex_b.htm#blinkership">blinker ship</a>
for an example perturbation of the spark. The diagram below shows
the smallest form of the Schick engine, using two <a href="lex_l.htm#lwss">LWSS</a>. It is also
possible to use two <a href="lex_m.htm#mwss">MWSSes</a> or two <a href="lex_h.htm#hwss">HWSSes</a>, or even an LWSS and an
HWSS.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OOOO..............$O...O.........O...$O...........OO....$.O..O..OO.....OOO.$......OOO......OOO$.O..O..OO.....OOO.$O...........OO....$O...O.........O...$OOOO..............$"
>OOOO..............
O...O.........O...
O...........OO....
.O..O..OO.....OOO.
......OOO......OOO
.O..O..OO.....OOO.
O...........OO....
O...O.........O...
OOOO..............
</a></pre></td></tr></table></center>
<p><a name=schickship>:</a><b>Schick ship</b> = <a href="#schickengine">Schick engine</a>
<p><a name=scorpion>:</a><b>scorpion</b> (p1)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...O...$.OOO...$O...OO.$O.O.O.O$.OO.O.O$.....O.$"
>...O...
.OOO...
O...OO.
O.O.O.O
.OO.O.O
.....O.
</a></pre></td></tr></table></center>
<p><a name=scrubber>:</a><b>scrubber</b> (p2) Found in 1971.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:....O......$..OOO......$.O.........$.O..OOO....$OO.O...O...$...O...O...$...O...O.OO$....OOO..O.$.........O.$......OOO..$......O....$"
>....O......
..OOO......
.O.........
.O..OOO....
OO.O...O...
...O...O...
...O...O.OO
....OOO..O.
.........O.
......OOO..
......O....
</a></pre></td></tr></table></center>
<p><a name=se>:</a><b>SE</b> = <a href="#switchengine">switch engine</a>
<p><a name=seal>:</a><b>seal</b> (<i>c</i>/6 diagonally, p6) The first diagonal <a href="lex_c.htm#c6spaceship">c/6 spaceship</a>, found
by Nicolay Beluchenko in September 2005.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...O..OO..........................$.OOO.O.O.O........................$.O..OOO..OO.......................$O..OOOOOO.O.OOO...................$.O..OOO.O.OOOOO...................$......O.O.O.O.....................$O.O...O.O.OOOOO...................$O..O.O..O.OO...O..................$...O..OO.......OOO................$.O...OOOOO.OOO..OO................$....O.........O...................$..O.O.........O...................$....OO.OOOOO...O..................$......O.OOO..O.....OO.............$......O..O...O.OOO.OO.............$........OO...OOO.O..O...O.........$........OO....OO.OOOO...OOO.......$...................O.O..O.........$.............O.O.....OO..OO.......$.............O..O.....O.OOO.....O.$.............O...O....OO..O...O..O$...............OOO.....OO........O$...............O.O..O..O.....OO..O$.................O..OO.OO.O..O....$................O.......O.O.......$.................O...OOOO.........$..................O...O...........$..................................$.......................O..........$......................O.O.........$.....................OO...........$.....................O.O..........$.....................OO...........$.......................O..........$......................O...........$"
>...O..OO..........................
.OOO.O.O.O........................
.O..OOO..OO.......................
O..OOOOOO.O.OOO...................
.O..OOO.O.OOOOO...................
......O.O.O.O.....................
O.O...O.O.OOOOO...................
O..O.O..O.OO...O..................
...O..OO.......OOO................
.O...OOOOO.OOO..OO................
....O.........O...................
..O.O.........O...................
....OO.OOOOO...O..................
......O.OOO..O.....OO.............
......O..O...O.OOO.OO.............
........OO...OOO.O..O...O.........
........OO....OO.OOOO...OOO.......
...................O.O..O.........
.............O.O.....OO..OO.......
.............O..O.....O.OOO.....O.
.............O...O....OO..O...O..O
...............OOO.....OO........O
...............O.O..O..O.....OO..O
.................O..OO.OO.O..O....
................O.......O.O.......
.................O...OOOO.........
..................O...O...........
..................................
.......................O..........
......................O.O.........
.....................OO...........
.....................O.O..........
.....................OO...........
.......................O..........
......................O...........
</a></pre></td></tr></table></center>
<p><a name=searchprogram>:</a><b>search program</b> A computer program or script that automates the search
for Life objects having certain desired properties. These are used
because the difficulty of finding previously unknown Life objects now
commonly exceeds the patience, speed, and accuracy of humans.
Various types of search programs are used for finding objects such as
<a href="#spaceship">spaceships</a>, <a href="lex_o.htm#oscillator">oscillators</a>, <a href="lex_d.htm#drifter">drifters</a>, <a href="lex_c.htm#catalyst">catalysts</a>, <a href="#soup">soups</a>,
<a href="lex_g.htm#gardenofeden">Gardens of Eden</a>, and <a href="#slowsalvo">slow salvos</a>.
<p>Some search programs generate <a href="lex_p.htm#partialresult">partial results</a> as they are
running, so even if they don't complete successfully, something of
use might still be salvaged from the run.
<p>Example search programs are <a href="lex_d.htm#dr">dr</a>, <a href="lex_l.htm#lifesrc">lifesrc</a>, <a href="lex_g.htm#gfind">gfind</a>, and
<a href="lex_b.htm#bellman">Bellman</a>.
<p>There are other types of programs which don't perform searches as
such, but instead perform large constructions. These are used to
correctly complete very complicated objects such as the
<a href="lex_c.htm#caterpillar">Caterpillar</a>, <a href="lex_g.htm#gemini">Gemini</a>, <a href="lex_c.htm#caterloopillar">Caterloopillar</a>, and
<a href="lex_u.htm#universalconstructor">universal constructor</a>-based spaceships such as the <a href="lex_d.htm#demonoid">Demonoids</a> and
<a href="lex_o.htm#orthogonoid">Orthogonoids</a>.
<p><a name=secondgliderdomain>:</a><b>second glider domain</b> The second glider domain of an <a href="lex_e.htm#edgeshooter">edge shooter</a> is
the set of spacetime offsets, relative to the <a href="lex_g.htm#glider">glider</a> <a href="#stream">stream</a>
emitted by the edge shooter, where a second independent glider stream
may be present without interfering with the edge shooter. This is
useful to know, because edge shooters are often used to generate
glider streams very close to other glider streams, to make for
example a <a href="#spaceship">spaceship</a> <a href="lex_g.htm#gun">gun</a> or <a href="lex_c.htm#converter">converter</a>.
<p><a name=secondnaturalglider>:</a><b>second natural glider</b> The glider produced at T=72 during the
<a href="lex_e.htm#evolution">evolution</a> of a <a href="lex_h.htm#herschel">Herschel</a>. This is the common edge-shooting glider
output used in the <a href="lex_n.htm#nw31">NW31</a> converter and several other converter
variants.
<p><a name=seed>:</a><b>seed</b> A <a href="lex_c.htm#constellation">constellation</a> of still lifes and/or oscillators, which can
be converted into another Life object when it is struck by one or
more gliders. Usually the resulting object is a rare still life or
spaceship, more complex than the original constellation. <a href="#spartan">Spartan</a>
single-glider (1G) seeds are more commonly seen than multi-glider
seeds, because a Spartan 1G seed can be readily constructed and
<a href="lex_t.htm#trigger">triggered</a> using a <a href="#slowsalvo">slow salvo</a>. See also <a href="lex_f.htm#freezedried">freeze-dried</a>. For
example, the following is a 14<a href="#sl">sL</a> 1G seed for a <i>c</i>/7 loafer
spaceship.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...................................O..........$..................................O...........$..................................OOO.........$.............OO...............................$..............O...............................$..............O.O.............................$...............OO.............................$..............................................$...O..........................................$..O.O.........................................$.O.O..........................................$.OO...........................................$..............OO..............................$.............O.O..............................$.............OO...............................$..............................................$..............................................$..............................................$....................OO........................$...................O.O........................$..........O.........O.........................$.........O.O....O.............................$..........OO...O.O............................$..............O.O.............................$..............OO..............................$..............................................$.............................................O$.........................OO................OOO$....................OO...OO...............O...$...................O..O...................OO..$.O.................O..O.......................$O.O.................OO........................$.OO...........................................$..............................................$..............................................$..............................................$.....................OO.......................$.....................O.O....OO................$......................O.....O.O...............$.............................OO...............$.................................OO...........$.................................OO...........$..............................................$..............................................$......................OO......................$.....................O..O.....................$.....................O..O.....................$......................OO......................$"
>...................................O..........
..................................O...........
..................................OOO.........
.............OO...............................
..............O...............................
..............O.O.............................
...............OO.............................
..............................................
...O..........................................
..O.O.........................................
.O.O..........................................
.OO...........................................
..............OO..............................
.............O.O..............................
.............OO...............................
..............................................
..............................................
..............................................
....................OO........................
...................O.O........................
..........O.........O.........................
.........O.O....O.............................
..........OO...O.O............................
..............O.O.............................
..............OO..............................
..............................................
.............................................O
.........................OO................OOO
....................OO...OO...............O...
...................O..O...................OO..
.O.................O..O.......................
O.O.................OO........................
.OO...........................................
..............................................
..............................................
..............................................
.....................OO.......................
.....................O.O....OO................
......................O.....O.O...............
.............................OO...............
.................................OO...........
.................................OO...........
..............................................
..............................................
......................OO......................
.....................O..O.....................
.....................O..O.....................
......................OO......................
</a></pre></td></tr></table></center>
<p><a name=seedsofdestructiongame>:</a><b>Seeds of Destruction Game</b> An interactive search application written
by Paul Chapman in 2013. Its primary purpose was to assist in the
design of self-destruct circuits in self-constructing circuitry. It
has also regularly been helpful in completing glider syntheses, and
was used to find the <a href="lex_1.htm#a-31c240">31c/240</a> base reaction for the <a href="#shieldbug">shield bug</a> and
<a href="lex_c.htm#centipede">Centipede</a> spaceships.
<p><a name=selfconstructing>:</a><b>self-constructing</b> A type of pattern, generally a <a href="lex_m.htm#macrospaceship">macro-spaceship</a>,
that contains encoded construction information about itself, and
makes a complete copy of itself using those instructions. The
<a href="lex_g.htm#gemini">Gemini</a>, <a href="lex_l.htm#linearpropagator">linear propagator</a>, <a href="#spiralgrowth">spiral growth</a> patterns, <a href="lex_d.htm#demonoid">Demonoids</a>
and <a href="lex_o.htm#orthogonoid">Orthogonoid</a> are examples of self-constructing patterns.
Self-constructing spaceships often have trivially adjustable speeds.
In many cases, the direction of travel can also be altered, less
easily, by changing the encoded <a href="lex_c.htm#constructionrecipe">construction recipe</a>. Compare
<a href="#selfsupporting">self-supporting</a>, <a href="lex_e.htm#elementary">elementary</a>.
<p><a name=selfsupporting>:</a><b>self-supporting</b> A type of pattern, specifically a <a href="lex_m.htm#macrospaceship">macro-spaceship</a>,
that constructs <a href="#signal">signals</a> or <a href="lex_t.htm#track">tracks</a> or other scaffolding to assist
its movement, but does not contain complete information about its own
structure. Examples include the Caterpillar, <a href="lex_c.htm#centipede">Centipede</a>,
<a href="lex_h.htm#halfbakedknightship">half-baked knightship</a>, <a href="lex_w.htm#waterbear">waterbear</a>, and the <a href="lex_c.htm#caterloopillar">Caterloopillars</a>.
<a href="lex_c.htm#caterpillar">Caterpillar</a> has been used as a general term for self-supporting
spaceships, but it is not very appropriate for the HBKs.
<p>In general a self-supporting pattern cannot be trivially adjusted
to alter its speed or direction. The variable speeds of the HBKs and
the Caterloopillars are exceptions, but their direction of travel is
fixed, and a specific Caterloopillar can't be made to change its
speed without completely rebuilding it. Compare <a href="#selfconstructing">self-constructing</a>,
<a href="lex_e.htm#elementary">elementary</a>.
<p><a name=semicenark>:</a><b>semi-cenark</b> Either of two <a href="#semisnark">semi-Snark</a> variants discovered by Tanner
Jacobi in November 2017. The name is due to the initial <a href="lex_c.htm#converter">converter</a>,
which produces a <a href="lex_c.htm#century">century</a> output for every two input <a href="lex_g.htm#glider">gliders</a>. The
minimum safe repeat time is 43 ticks for the smaller initial
<a href="lex_c.htm#catalyst">catalyst</a> shown in <a href="lex_c.htm#ccsemicenark">CC semi-cenark</a> and <a href="lex_c.htm#cpsemicenark">CP semi-cenark</a>, or 42
ticks with the slightly larger catalyst variant shown below. There
is also <a href="lex_o.htm#overclocking">overclocking</a> possible at period 36, 38, or 39. The reset
glider can be followed immediately by a new trigger glider, as shown
below, so the minimum repeat time for an <a href="lex_i.htm#intermittentstream">intermittent stream</a> of
gliders is only 50 ticks.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:O.O.................................$.OO.................................$.O..................................$....................................$....................................$....................................$....................................$....................................$....................................$.........O.O........................$..........OO........................$..........O.........................$.............O......................$..............OO....................$.............OO.....................$.............................O......$...........................OOO......$..........................O.........$..........................OO........$....................................$....................................$......................O.............$..............OO.......OO..O........$..............O..O....OO..O.O.......$............OO..OO........OO........$...........O..OO....................$...........OO...OO..................$................O.O.................$.................O..................$..................................OO$................................O..O$.....................OO.........OOO.$......................O......O......$...................OOO.......OOOO...$...................O............O...$...............................O....$...............................OO...$"
>O.O.................................
.OO.................................
.O..................................
....................................
....................................
....................................
....................................
....................................
....................................
.........O.O........................
..........OO........................
..........O.........................
.............O......................
..............OO....................
.............OO.....................
.............................O......
...........................OOO......
..........................O.........
..........................OO........
....................................
....................................
......................O.............
..............OO.......OO..O........
..............O..O....OO..O.O.......
............OO..OO........OO........
...........O..OO....................
...........OO...OO..................
................O.O.................
.................O..................
..................................OO
................................O..O
.....................OO.........OOO.
......................O......O......
...................OOO.......OOOO...
...................O............O...
...............................O....
...............................OO...
</a></pre></td></tr></table></center>
<p><a name=semisnark>:</a><b>semi-Snark</b> Any small <a href="#stable">stable</a> <a href="#signal">signal</a> <a href="lex_c.htm#conduit">conduit</a> that produces one
output glider for every two input gliders, with a 90 degree
reflection. These can act as period-doublers for any glider stream
whose period is at least equal to their repeat time, and so adding
one of these to a single glider <a href="lex_g.htm#gun">gun</a> often results in a pattern much
smaller than the older <a href="lex_t.htm#technology">technology</a> of crossing the output of two
guns.
<p>The available semi-Snarks differ in their complexity, size, repeat
time, and the colour of their output gliders. The <a href="lex_c.htm#ccsemisnark">CC semi-Snark</a>
was the first one found, and the term "semi-Snark" is often used
specifically for this object. The "CC" prefix stands for
<a href="lex_c.htm#colourchanging">colour-changing</a>, by contrast with the more recently discovered
<a href="lex_c.htm#colourpreserving">colour-preserving</a> <a href="lex_c.htm#cpsemisnark">CP semi-Snark</a>.
<p>There are also CC and CP variants of a semi-Snark based on a
two-<a href="lex_g.htm#glider">glider</a> to <a href="lex_c.htm#century">century</a> <a href="lex_c.htm#converter">converter</a> discovered by Tanner Jacobi in
November 2017. These <a href="#semicenark">semi-cenarks</a> are the fastest semi-Snarks
known as of July 2018, with a <a href="lex_r.htm#repeattime">repeat time</a> as low as 50 ticks, or a
periodic input rate as low as 36 ticks.
<p><a name=sesquihat>:</a><b>sesquihat</b> (p1) Halfway between a <a href="lex_h.htm#hat">hat</a> and a <a href="lex_t.htm#twinhat">twinhat</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:....O..$OO.O.O.$.O.O.O.$.O.O.OO$..O....$"
>....O..
OO.O.O.
.O.O.O.
.O.O.OO
..O....
</a></pre></td></tr></table></center>
<p><a name=sgr>:</a><b>SGR</b> Abbreviation for <a href="#stable">stable</a> <a href="lex_g.htm#glider">glider</a> <a href="lex_r.htm#reflector">reflector</a>. This term is no
longer in use.
<p><a name=shieldbug>:</a><b>shield bug</b> (31<i>c</i>/240 orthogonally, p240) The first 31<i>c</i>/240
<a href="lex_m.htm#macrospaceship">macro-spaceship</a>, constructed by Dave Greene on September 9, 2014.
<p><a name=shillelagh>:</a><b>shillelagh</b> (p1)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO...$O..OO$.OO.O$"
>OO...
O..OO
.OO.O
</a></pre></td></tr></table></center>
<p><a name=ship>:</a><b>ship</b> (p1) The term is also used as a synonym of <a href="#spaceship">spaceship</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO.$O.O$.OO$"
>OO.
O.O
.OO
</a></pre></td></tr></table></center>
<p>A ship can be used as a <a href="lex_c.htm#catalyst">catalyst</a> in some situations. For
example, it can suppress two of the <a href="lex_b.htm#blinker">blinkers</a> from an evolving
<a href="lex_t.htm#trafficlight">traffic light</a>:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...OO.$...O.O$....OO$......$O.....$OO....$O.....$"
>...OO.
...O.O
....OO
......
O.....
OO....
O.....
</a></pre></td></tr></table></center>
It is also a one-glider <a href="#seed">seed</a> for the <a href="lex_e.htm#engine">engine</a> of the
<a href="lex_q.htm#queenbeeshuttle">queen bee shuttle</a>:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OOO..OO.$..O..O.O$.O....OO$"
>OOO..OO.
..O..O.O
.O....OO
</a></pre></td></tr></table></center>
<p><a name=shipinabottle>:</a><b>ship in a bottle</b> (p16) Found by Bill Gosper in August 1994. See also
<a href="lex_b.htm#bottle">bottle</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:....OO......OO....$...O..O....O..O...$...O.O......O.O...$.OO..OOO..OOO..OO.$O......O..O......O$O.OO..........OO.O$.O.O..........O.O.$...OO...OO...OO...$.......O.O........$.......OO.........$...OO........OO...$.O.O..........O.O.$O.OO..........OO.O$O......O..O......O$.OO..OOO..OOO..OO.$...O.O......O.O...$...O..O....O..O...$....OO......OO....$"
>....OO......OO....
...O..O....O..O...
...O.O......O.O...
.OO..OOO..OOO..OO.
O......O..O......O
O.OO..........OO.O
.O.O..........O.O.
...OO...OO...OO...
.......O.O........
.......OO.........
...OO........OO...
.O.O..........O.O.
O.OO..........OO.O
O......O..O......O
.OO..OOO..OOO..OO.
...O.O......O.O...
...O..O....O..O...
....OO......OO....
</a></pre></td></tr></table></center>
<p><a name=shiponboat>:</a><b>ship on boat</b> = <a href="#shiptieboat">ship tie boat</a>
<p><a name=shiponship>:</a><b>ship on ship</b> = <a href="#shiptie">ship-tie</a>
<p><a name=shiptie>:</a><b>ship-tie</b> (p1) The name is by analogy with <a href="lex_b.htm#boattie">boat-tie</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO....$O.O...$.OO...$...OO.$...O.O$....OO$"
>OO....
O.O...
.OO...
...OO.
...O.O
....OO
</a></pre></td></tr></table></center>
<p><a name=shiptieboat>:</a><b>ship tie boat</b> (p1)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO....$O.O...$.OO...$...OO.$...O.O$....O.$"
>OO....
O.O...
.OO...
...OO.
...O.O
....O.
</a></pre></td></tr></table></center>
<p><a name=shortkeys>:</a><b>short keys</b> (p3) Found by Dean Hickerson, August 1989. See also
<a href="lex_b.htm#bentkeys">bent keys</a> and <a href="lex_o.htm#oddkeys">odd keys</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.O........O.$O.OOO..OOO.O$.O..O..O..O.$....O..O....$"
>.O........O.
O.OOO..OOO.O
.O..O..O..O.
....O..O....
</a></pre></td></tr></table></center>
<p><a name=shotgun>:</a><b>shotgun</b> A <a href="lex_g.htm#gun">gun</a> that fires a <a href="#salvo">salvo</a> of multiple <a href="#spaceship">spaceships</a>, almost
always <a href="lex_g.htm#glider">gliders</a>, on parallel <a href="lex_l.htm#lane">lanes</a>. Two to four shotguns are
often combined to turn a <a href="lex_g.htm#glidersynthesis">glider synthesis</a> into a gun or <a href="lex_f.htm#factory">factory</a>
for that synthesis.
<p><a name=shoulder>:</a><b>shoulder</b> The fixed upper end of a <a href="lex_c.htm#constructionarm">construction arm</a>, generally
consisting of one or more glider <a href="lex_g.htm#gun">guns</a> or <a href="lex_e.htm#edgeshooter">edge shooters</a> aimed at
an <a href="lex_e.htm#elbow">elbow</a> object.
<p><a name=shuttle>:</a><b>shuttle</b> Any <a href="lex_o.htm#oscillator">oscillator</a> which consists of an active region moving
back and forth between stabilizing objects. The most well-known
examples are the <a href="lex_q.htm#queenbeeshuttle">queen bee shuttle</a> (which has often been called
simply "the shuttle") and the <a href="lex_t.htm#twinbeesshuttle">twin bees shuttle</a>. See also
<a href="lex_p.htm#p54shuttle">p54 shuttle</a>, <a href="lex_p.htm#p130shuttle">p130 shuttle</a> and <a href="lex_e.htm#eureka">Eureka</a>. Another example is the
p72 <a href="lex_r.htm#rpentomino">R-pentomino</a> shuttle that forms part of the pattern given under
<a href="lex_f.htm#factory">factory</a>.
<p><a name=siamese>:</a><b>siamese</b> A term used in naming certain <a href="#stilllife">still lifes</a> (and the <a href="#stator">stator</a>
part of certain <a href="lex_o.htm#oscillator">oscillators</a>). It indicates that the object
consists of two smaller objects sharing two or more cells. See
<a href="#snakesiamesesnake">snake siamese snake</a> and <a href="lex_l.htm#loafsiamesebarge">loaf siamese barge</a> for examples.
<p><a name=side>:</a><b>side</b> Half a <a href="#sidewalk">sidewalk</a>. In itself this is unstable and requires an
<a href="lex_i.htm#inductioncoil">induction coil</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO...$O.OOO$....O$"
>OO...
O.OOO
....O
</a></pre></td></tr></table></center>
<p><a name=sidecar>:</a><b>sidecar</b> A small <a href="lex_t.htm#tagalong">tagalong</a> for an <a href="lex_h.htm#hwss">HWSS</a> that was found by Hartmut
Holzwart in 1992. The resulting <a href="#spaceship">spaceship</a> (shown below) has a
<a href="lex_p.htm#phase">phase</a> with only 24 cells, making it in this respect the smallest
known spaceship other than the <a href="#standardspaceship">standard spaceships</a> and some trivial
two-spaceship <a href="lex_f.htm#flotilla">flotillas</a> derived from them. Note also that an HWSS
can support two sidecars at once.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.O......$O.....O.$O.....O.$OOOOO.O.$........$....OO..$..O....O$.O......$.O.....O$.OOOOOO.$"
>.O......
O.....O.
O.....O.
OOOOO.O.
........
....OO..
..O....O
.O......
.O.....O
.OOOOOO.
</a></pre></td></tr></table></center>
<p><a name=sideshootinggun>:</a><b>side-shooting gun</b> = <a href="#slidegun">slide gun</a>
<p><a name=sidesnagger>:</a><b>sidesnagger</b> A <a href="#spartan">Spartan</a> eater found by Chris Cain in May 2015 with
functionality similar to the <a href="lex_e.htm#eater5">eater5</a>, as shown below. It has one
<a href="lex_l.htm#lane">lane</a> less diagonal <a href="lex_c.htm#clearance">clearance</a> on the high-clearance side than
other eater5 variants, due to the presence of the boat. A good use
of the sidesnagger can be seen in <a href="lex_p.htm#p130shuttle">p130 shuttle</a>. See also
<a href="lex_h.htm#highwayrobber">highway robber</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..O.............$O.O.............$.OO.............$................$................$................$.........O......$........O.......$........OOO.....$................$................$.........O......$........O.O.....$.......O..O...OO$........OO....OO$....O...........$...O.O..........$...OO...........$.........OO.....$.........OO.....$"
>..O.............
O.O.............
.OO.............
................
................
................
.........O......
........O.......
........OOO.....
................
................
.........O......
........O.O.....
.......O..O...OO
........OO....OO
....O...........
...O.O..........
...OO...........
.........OO.....
.........OO.....
</a></pre></td></tr></table></center>
<p><a name=sidetracking>:</a><b>side-tracking</b> See <a href="lex_u.htm#universalconstructor">universal constructor</a>.
<p><a name=sidewalk>:</a><b>sidewalk</b> (p1)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.OO.OO$..O.O.$.O..O.$.O.O..$OO.OO.$"
>.OO.OO
..O.O.
.O..O.
.O.O..
OO.OO.
</a></pre></td></tr></table></center>
<p><a name=siesta>:</a><b>siesta</b> (p5) Found by Dave Buckingham in 1973. Compare <a href="#sombreros">sombreros</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...........OO...$...OO.....O.O...$...O.O....O.....$.....O...OO.O...$...O.OO.....OOO.$.OOO.....O.O...O$O...O.O.....OOO.$.OOO.....OO.O...$...O.OO...O.....$.....O....O.O...$...O.O.....OO...$...OO...........$"
>...........OO...
...OO.....O.O...
...O.O....O.....
.....O...OO.O...
...O.OO.....OOO.
.OOO.....O.O...O
O...O.O.....OOO.
.OOO.....OO.O...
...O.OO...O.....
.....O....O.O...
...O.O.....OO...
...OO...........
</a></pre></td></tr></table></center>
<p><a name=signal>:</a><b>signal</b> Movement of information through the Life universe. Signals
can be carried by <a href="#spaceship">spaceships</a>, <a href="lex_f.htm#fuse">fuses</a>, <a href="lex_d.htm#drifter">drifters</a>, or <a href="lex_c.htm#conduit">conduits</a>.
Spaceships can only transfer a signal at the speed of the spaceship,
while fuses can transfer a signal at speeds up to the
<a href="#speedoflight">speed of light</a>.
<p>In practice, many signals are encoded as the presence or absence of
a <a href="lex_g.htm#glider">glider</a> or other spaceship at a particular point at a particular
time. Such signals can be combined by the collision of gliders to
form logic operations such as AND, OR, and NOT gates. Signals can be
duplicated using <a href="lex_g.htm#gliderduplicator">glider duplicators</a> or other <a href="lex_f.htm#fanout">fanout</a> devices, and
can be used up by causing <a href="lex_p.htm#perturbation">perturbations</a> on other parts of the Life
object.
<p>Signals are used in <a href="lex_h.htm#herschelconduit">Herschel conduit</a> circuitry,
<a href="lex_u.htm#universalconstructor">universal constructors</a>, <a href="lex_m.htm#macrospaceship">macro-spaceships</a>, and other computational
patterns such as the <a href="lex_p.htm#picalculator">pi calculator</a> and <a href="lex_o.htm#osqrtlogt">Osqrtlogt</a> patterns.
<p><a name=signalelbow>:</a><b>signal elbow</b> A <a href="lex_c.htm#conduit">conduit</a> with <a href="#signal">signal</a> output 90 degrees from its
input. This term is commonly used only for signal <a href="lex_w.htm#wire">wires</a>,
particularly <a href="lex_1.htm#a-2c3">2c/3</a> signals. A <a href="#snark">Snark</a> could reasonably be called a
"glider elbow", but <a href="lex_g.htm#gliderreflector">glider reflector</a> is the standard term. A
signal elbow with a <a href="lex_r.htm#recoverytime">recovery time</a> less than 20 ticks would enable a
trivial proof that Conway's Life is <a href="lex_o.htm#omniperiodic">omniperiodic</a>.
<p>A near miss is the following elbow-like <a href="lex_c.htm#converter">converter</a> found by Dean
Hickerson. It successfully turns a 2<i>c</i>/3 signal by 90 degrees, but
unfortunately changes it to a double-length signal in the process.
This means that further copies of the converter can not be appended
(e.g., to make a closed loop).
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:........................O..O......$........................OOOOOO....$..............................O.OO$......................OOOOO.O.O.OO$.....................O......O.O...$.....................OOOOO..O.O...$..................O.......O.OO....$..................OOOOOO..O.......$........................O.O.......$................OOOOOO..O.OO......$..........OO...O......O.O.........$.........O..O..OOOOO..O.O.........$........O.OOO.......O.OO..........$....OO.O.O...OOOOO..O.............$.....O.O...O......O.O.............$.....O.O..OOOOOO..O.OO............$...O.O.O.O......O.O...............$..O.OO..O.OOOO..O.O...............$..O...O.O.O...O.OO................$OO.OO.O.O...O.O...................$.O.O..O.OOOO.O.OOO................$O..O.O.......O...O................$.OOO..OOOOOOOO....................$....O.O...........................$...OO.O..OOOOOOO..................$..O..OO.O.......O.................$..OO....O..OOOOOO.................$........O.O.......................$.......OO.O..OOOOOO...............$..........O.O......O..............$..........O.O..OOOOO..............$...........OO.O.......O...........$..............O..OOOOOO...........$..............O.O.................$.............OO.O..OOOOOO.........$................O.O......O.OO.....$................O.O..OOOOO.OO.....$.................OO.O.............$....................O..OOOOOO.....$....................O.O.....O.....$...................OO.O..OOO......$......................O.O.....OO..$......................O..O....OO..$.......................OO.........$"
>........................O..O......
........................OOOOOO....
..............................O.OO
......................OOOOO.O.O.OO
.....................O......O.O...
.....................OOOOO..O.O...
..................O.......O.OO....
..................OOOOOO..O.......
........................O.O.......
................OOOOOO..O.OO......
..........OO...O......O.O.........
.........O..O..OOOOO..O.O.........
........O.OOO.......O.OO..........
....OO.O.O...OOOOO..O.............
.....O.O...O......O.O.............
.....O.O..OOOOOO..O.OO............
...O.O.O.O......O.O...............
..O.OO..O.OOOO..O.O...............
..O...O.O.O...O.OO................
OO.OO.O.O...O.O...................
.O.O..O.OOOO.O.OOO................
O..O.O.......O...O................
.OOO..OOOOOOOO....................
....O.O...........................
...OO.O..OOOOOOO..................
..O..OO.O.......O.................
..OO....O..OOOOOO.................
........O.O.......................
.......OO.O..OOOOOO...............
..........O.O......O..............
..........O.O..OOOOO..............
...........OO.O.......O...........
..............O..OOOOOO...........
..............O.O.................
.............OO.O..OOOOOO.........
................O.O......O.OO.....
................O.O..OOOOO.OO.....
.................OO.O.............
....................O..OOOOOO.....
....................O.O.....O.....
...................OO.O..OOO......
......................O.O.....OO..
......................O..O....OO..
.......................OO.........
</a></pre></td></tr></table></center>
<p>Relatively small <a href="lex_c.htm#composite">composite</a> <a href="lex_m.htm#mwss">MWSS</a> elbows can now be constructed,
using Tanner Jacobi's 2015 discovery of a small <a href="lex_h.htm#htomwss">H-to-MWSS</a>
component. For example, the <a href="lex_o.htm#orthogonoid">Orthogonoid</a> includes a
constructor/reflector that reflects an MWSS stream by 180 degrees,
but it can be trivially reconfigured to make a 90-degree MWSS elbow.
<p><a name=silvergtoh>:</a><b>Silver G-to-H</b> A variant of the <a href="#silverreflector">Silver reflector</a> made by
substituting an <a href="lex_f.htm#fx119">Fx119</a> conduit for the final <a href="lex_n.htm#nw31">NW31</a>, allowing a
Herschel output as well as the beehive-annihilating reset glider. It
is still <a href="#spartan">Spartan</a>, and as long as the Fx119 is followed by a
<a href="lex_d.htm#dependentconduit">dependent conduit</a>, it retains the faster 497-tick <a href="lex_r.htm#recoverytime">recovery time</a>.
<p><a name=silverreflector>:</a><b>Silver reflector</b> A <a href="#stable">stable</a> <a href="lex_g.htm#gliderreflector">glider reflector</a> found by Stephen
Silver in November 1998, by substituting an <a href="lex_n.htm#nw31">NW31</a> converter for the
second <a href="lex_f.htm#fx77">Fx77</a> conduit in the <a href="lex_c.htm#callahangtoh">Callahan G-to-H</a> found a few days
previous. The repeat time is 497 ticks:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:........O.............O.......................................$......O.O...........OOO.......................................$.......OO..........O..........................................$...................OO.........................................$....OO........................................................$.....O........................................................$.....O.O......................................................$......OO..........O...........................................$.................O.O..........................................$.................O.O..........................................$..................O....OO.....................................$......OO...............O.O....................................$.....O.O.................O....................................$.....O...................OO...................................$....OO........................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$...............OO.............................................$...............OO.............................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$...OO.........................................................$....O.........................................................$....O.O.......................................................$.....OO.......................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$......OO...............OO.....................................$......OO...............O.O....................................$.........................O....................................$.........................OO...................................$..............................................................$..............................................................$..............................................................$..............................................................$..............................................................$...................O..........................................$.................OOO..........................................$................O.............................................$................OO...................OO.......................$....................OO................O.......................$.....................O................O.O.....................$...................O...................OO.....................$...................OO.........................................$..............................................................$..............................................................$............................................................OO$............................................................OO$..............................................................$......................OO......................................$...OO.................OO......................................$...OO.........................................................$..............................................................$..............................................................$..OO..........................................................$...O..........................................................$OOO............OO.............................................$O..............O..............................................$................OOO...........................................$..................O...........................................$..............................................................$..................................................OO..........$..................................................OO..........$"
>........O.............O.......................................
......O.O...........OOO.......................................
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.....O.O.................O....................................
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.....................O................O.O.....................
...................O...................OO.....................
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OOO............OO.............................................
O..............O..............................................
................OOO...........................................
..................O...........................................
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..................................................OO..........
..................................................OO..........
</a></pre></td></tr></table></center>
<p><a name=silversp5>:</a><b>Silver's p5</b> (p5) The following oscillator found by Stephen Silver in
February 2000:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO.........$O..........$.O..O......$...OO......$...O...O.OO$..O....OO.O$..OO.......$"
>OO.........
O..........
.O..O......
...OO......
...O...O.OO
..O....OO.O
..OO.......
</a></pre></td></tr></table></center>
<p>As this has no <a href="#spark">spark</a>, it appears useless. Nonetheless, in March
2000, David Eppstein found a way to use it to reduce the size of Noam
Elkies' p5 <a href="lex_r.htm#reflector">reflector</a>.
<p><a name=simkinglidergun>:</a><b>Simkin glider gun</b> (p120) A <a href="lex_h.htm#herschel">Herschel</a>-based glider gun discovered by
Michael Simkin in April 2015. It consists of a Herschel running
through two <a href="lex_b.htm#b60">B60</a> conduits. In terms of its 36-cell minimum
population, it is one of the smallest known guns, sharing the record
with the <a href="lex_g.htm#gosperglidergun">Gosper glider gun</a>. In the double-barreled form, as well as
the <a href="lex_p.htm#pseudo">pseudo</a>-period, <a href="#snake">snake</a>-stabilized form shown below, it is the
absolute record holder.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO.....OO........................$OO.....OO........................$.................................$....OO...........................$....OO...........................$.................................$.................................$.................................$.................................$......................OO.OO......$.....................O.....O.....$.....................O......O..OO$.....................OOO...O...OO$..........................O......$.................................$.................................$.................................$.................................$........................O.OO.....$........................OO.O.....$"
>OO.....OO........................
OO.....OO........................
.................................
....OO...........................
....OO...........................
.................................
.................................
.................................
.................................
......................OO.OO......
.....................O.....O.....
.....................O......O..OO
.....................OOO...O...OO
..........................O......
.................................
.................................
.................................
.................................
........................O.OO.....
........................OO.O.....
</a></pre></td></tr></table></center>
<p><a name=singlearm>:</a><b>single-arm</b> A type of <a href="lex_u.htm#universalconstructor">universal constructor</a> using just one
construction arm and <a href="#slowsalvo">slow salvo</a> techniques to construct, usually,
<a href="#spartan">Spartan</a> or near-Spartan circuitry. Compare <a href="lex_t.htm#twoarm">two-arm</a>.
<p><a name=singlechannel>:</a><b>single-channel</b> A type of <a href="lex_u.htm#universalconstructor">universal constructor</a> discovered and
developed by Simon Ekstr&ouml;m and others starting in December 2015. The
initial <a href="lex_e.htm#elbowoperation">elbow operation</a> toolkit was near-minimal, with just one
<a href="lex_p.htm#push">push</a>, one <a href="lex_p.htm#pull">pull</a>, and one output glider of each colour (see
<a href="lex_c.htm#colourofaglider">colour of a glider</a>). Later searches produced a much larger and
more efficient library.
<p>Single-channel <a href="lex_r.htm#recipe">recipes</a> consist of a <a href="#stream">stream</a> of <a href="lex_g.htm#glider">gliders</a> on a
single <a href="lex_l.htm#lane">lane</a> and aimed at a <a href="lex_c.htm#constructionelbow">construction elbow</a>, usually separated
from each other by at least 90 <a href="lex_t.htm#tick">ticks</a>. In spite of these strict
limitations, single-channel recipes can be made to do surprising
things. For example, it is possible to build a <a href="#snark">Snark</a> directly on
the <a href="lex_c.htm#constructionlane">construction lane</a> of an active construction arm, starting from
a single <a href="lex_e.htm#elbow">elbow</a> <a href="lex_b.htm#block">block</a>. This can allow the arm to reach
efficiently around complex obstructions by bending itself through
multiple <a href="lex_l.htm#losslesselbow">lossless elbows</a>. Known recipes can also remove an elbow
when it is no longer needed, by controlled demolition of the Snark.
<p>As of June 2018, almost all single-channel recipes are made up of
<a href="#singleton">singletons</a> and <a href="#synchronized">synchronized</a> pairs of gliders, but no synchronized
triplets or larger groups. This is not an inherent limitation of
single-channel construction, but rather a limitation in the
<a href="#searchprogram">search program</a> used to find currently known single-channel
<a href="lex_t.htm#toolkit">toolkits</a>.
<p>A useful byproduct of this limitation is that single-channel
recipes can be trivially adjusted to allow them to safely cross
perpendicular data streams, including other single-channel recipes
(or earlier parts of the same recipe). To avoid collisions with a
crossing stream, each singleton glider or glider pair can safely be
delayed by any even number of ticks, or technically by any multiple
of the period of the current <a href="lex_i.htm#intermediatetarget">intermediate target</a>. The final result
of the construction will not be affected.
<p><a name=singlechanneldemonoid>:</a><b>single-channel Demonoid</b> See <a href="lex_d.htm#demonoid">Demonoid</a>.
<p><a name=singlelane>:</a><b>single-lane</b> = <a href="#singlechannel">single-channel</a>.
<p><a name=singleton>:</a><b>singleton</b> In <a href="#singlechannel">single-channel</a> <a href="lex_r.htm#recipe">recipes</a>, a glider that is not
<a href="#synchronized">synchronized</a> with a neighboring glider in its <a href="#stream">stream</a>. Compare
<a href="lex_g.htm#gliderpair">glider pair</a>.
<p><a name=singularflipflop>:</a><b>singular flip flop</b> (p2) Found by Robert Wainwright, July 1972.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..O...$..O.O.$O....O$OOOOOO$......$..OO..$..OO..$"
>..O...
..O.O.
O....O
OOOOOO
......
..OO..
..OO..
</a></pre></td></tr></table></center>
<p><a name=sinkingship>:</a><b>sinking ship</b> = <a href="lex_c.htm#canoe">canoe</a>
<p><a name=sirrobin>:</a><b>Sir Robin</b> ((2,1)<i>c</i>/6, p6) The first elementary <a href="lex_k.htm#knightship">knightship</a> in
Conway's Game of Life, found by Adam P. Goucher on March 6, 2018,
based on a partial by Tomas Rokicki.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:....OO.........................$....O..O.......................$....O...O......................$......OOO......................$..OO......OOOO.................$..O.OO....OOOO.................$.O....O......OOO...............$..OOOO....OO...O...............$O.........OO...................$.O...O.........................$......OOO..OO..O...............$..OO.......O....O..............$.............O.OO..............$..........OO......O............$...........OO.OOO.O............$..........OO...O..O............$..........O.O..OO..............$..........O..O.O.O.............$..........OOO......O...........$...........O.O.O...O...........$..............OO.O.O...........$...........O......OOO..........$...............................$...........O.........O.........$...........O...O......O........$............O.....OOOOO........$............OOO................$................OO.............$.............OOO..O............$...........O.OOO.O.............$..........O...O..O.............$...........O....OO.OOO.........$.............OOOO.O....OO......$.............O.OOOO....OO......$...................O...........$....................O..OO......$....................OO.........$.....................OOOOO.....$.........................OO....$...................OOO......O..$....................O.O...O.O..$...................O...O...O...$...................O...OO......$..................O......O.OOO.$...................OO...O...OO.$....................OOOO..O..O.$......................OO...O...$.....................O.........$.....................OO.O......$....................O..........$...................OOOOO.......$...................O....O......$..................OOO.OOO......$..................O.OOOOO......$..................O............$....................O..........$................O....OOOO......$....................OOOO.OO....$.................OOO....O......$........................O.O....$............................O..$........................O..OO..$.........................OOO...$......................OO.......$.....................OOO.....O.$........................OO..O.O$.....................O..OOO.O.O$......................OO.O..O..$........................O.O..OO$..........................OO...$......................OOO....O.$......................OOO....O.$.......................OO...OOO$........................OO.OO..$.........................OO....$.........................O.....$...............................$........................OO.....$..........................O....$"
>....OO.........................
....O..O.......................
....O...O......................
......OOO......................
..OO......OOOO.................
..O.OO....OOOO.................
.O....O......OOO...............
..OOOO....OO...O...............
O.........OO...................
.O...O.........................
......OOO..OO..O...............
..OO.......O....O..............
.............O.OO..............
..........OO......O............
...........OO.OOO.O............
..........OO...O..O............
..........O.O..OO..............
..........O..O.O.O.............
..........OOO......O...........
...........O.O.O...O...........
..............OO.O.O...........
...........O......OOO..........
...............................
...........O.........O.........
...........O...O......O........
............O.....OOOOO........
............OOO................
................OO.............
.............OOO..O............
...........O.OOO.O.............
..........O...O..O.............
...........O....OO.OOO.........
.............OOOO.O....OO......
.............O.OOOO....OO......
...................O...........
....................O..OO......
....................OO.........
.....................OOOOO.....
.........................OO....
...................OOO......O..
....................O.O...O.O..
...................O...O...O...
...................O...OO......
..................O......O.OOO.
...................OO...O...OO.
....................OOOO..O..O.
......................OO...O...
.....................O.........
.....................OO.O......
....................O..........
...................OOOOO.......
...................O....O......
..................OOO.OOO......
..................O.OOOOO......
..................O............
....................O..........
................O....OOOO......
....................OOOO.OO....
.................OOO....O......
........................O.O....
............................O..
........................O..OO..
.........................OOO...
......................OO.......
.....................OOO.....O.
........................OO..O.O
.....................O..OOO.O.O
......................OO.O..O..
........................O.O..OO
..........................OO...
......................OOO....O.
......................OOO....O.
.......................OO...OOO
........................OO.OO..
.........................OO....
.........................O.....
...............................
........................OO.....
..........................O....
</a></pre></td></tr></table></center>
<p><a name=sixls>:</a><b>six Ls</b> (p3) This is a compact form of <a href="lex_l.htm#loadingdock">loading dock</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...O...$.OOO..O$O...OOO$OOO....$....OOO$OOO...O$O..OOO.$...O...$"
>...O...
.OOO..O
O...OOO
OOO....
....OOO
OOO...O
O..OOO.
...O...
</a></pre></td></tr></table></center>
<p><a name=sixtynine>:</a><b>sixty-nine</b> (p4) Found by Robert Wainwright, October 1978.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.........O...........$........O.O..........$.....................$......O...OO.........$.....O.....O.........$......O.O............$........OO......O....$................O....$..O.....OO....OOO....$..O...........OO.....$OOO.......OO..OO..OOO$OO......O.OO....OOO..$OO..OOO.O.O.....OOO..$..OOO................$..OOO......O.........$..........O.O........$.....................$........O...OO.......$.......O.....O.......$........O.O..........$..........OO.........$"
>.........O...........
........O.O..........
.....................
......O...OO.........
.....O.....O.........
......O.O............
........OO......O....
................O....
..O.....OO....OOO....
..O...........OO.....
OOO.......OO..OO..OOO
OO......O.OO....OOO..
OO..OOO.O.O.....OOO..
..OOO................
..OOO......O.........
..........O.O........
.....................
........O...OO.......
.......O.....O.......
........O.O..........
..........OO.........
</a></pre></td></tr></table></center>
<p><a name=skewedquad>:</a><b>skewed quad</b> (p2)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.OO....$.O...OO$..O.O.O$.......$O.O.O..$OO...O.$....OO.$"
>.OO....
.O...OO
..O.O.O
.......
O.O.O..
OO...O.
....OO.
</a></pre></td></tr></table></center>
<p><a name=skewedtrafficlight>:</a><b>skewed traffic light</b> (p3) Found by Robert Wainwright, August 1989.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.............OO.........$............O..O........$.............O.O........$.........OO...O.........$..........O.OO..........$............O...........$............O...........$........................$OO........OOO......O....$OOOO.O........O...OO....$O.O..OOO.O....O.........$.........O....O.OOO..O.O$....OO...O........O.OOOO$....O......OOO........OO$........................$...........O............$...........O............$..........OO.O..........$.........O...OO.........$........O.O.............$........O..O............$.........OO.............$"
>.............OO.........
............O..O........
.............O.O........
.........OO...O.........
..........O.OO..........
............O...........
............O...........
........................
OO........OOO......O....
OOOO.O........O...OO....
O.O..OOO.O....O.........
.........O....O.OOO..O.O
....OO...O........O.OOOO
....O......OOO........OO
........................
...........O............
...........O............
..........OO.O..........
.........O...OO.........
........O.O.............
........O..O............
.........OO.............
</a></pre></td></tr></table></center>
<p><a name=sl>:</a><b>sL</b> Abbreviation for <a href="#stilllife">still life</a>, used most often in rough
measurements of the complexity of a <a href="#spartan">Spartan</a> constellation.
<p><a name=slidegun>:</a><b>slide gun</b> A <a href="lex_g.htm#gun">gun</a> which fires sideways from an extending arm. The
arm consists of streams of <a href="#spaceship">spaceships</a> which are pushing a pattern
away from the body of the gun and releasing an output spaceship every
time they do so. Each output spaceship therefore travels along a
different path.
<p>Dieter Leithner constructed the first slide gun in July 1994
(although he used the term "side shooting gun"). The following
pattern shows the key reaction of this slide gun. The three gliders
shown will push the block one cell diagonally, thereby extending the
length of the arm by one cell, and at the same time they release an
output glider sideways. (In 1999, Jason Summers constructed slide
guns using other reactions.)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..............OO.$..............OO.$........OOO......$..........O......$.........O.....OO$..............O.O$................O$.................$.................$.................$.................$.................$.................$.................$.................$.................$.................$.O...............$.OO..............$O.O..............$"
>..............OO.
..............OO.
........OOO......
..........O......
.........O.....OO
..............O.O
................O
.................
.................
.................
.................
.................
.................
.................
.................
.................
.................
.O...............
.OO..............
O.O..............
</a></pre></td></tr></table></center>
<p><a name=slidingblockmemory>:</a><b>sliding block memory</b> A memory register whose value is stored as the
position of a <a href="lex_b.htm#block">block</a>. The block can be moved by means of <a href="lex_g.htm#glider">glider</a>
collisions. See <a href="lex_b.htm#blockpusher">block pusher</a> for an example.
<p>In Conway's original formulation (as part of his proof of the
existence of a <a href="lex_u.htm#universalcomputer">universal computer</a> in Life) two gliders were used to
pull the block inwards by three diagonal spaces, as shown below, and
thirty gliders were used to push it out by the same amount.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO..........$OO..........$............$............$............$.........OOO$OOO......O..$O.........O.$.O..........$"
>OO..........
OO..........
............
............
............
.........OOO
OOO......O..
O.........O.
.O..........
</a></pre></td></tr></table></center>
<p>Dean Hickerson later greatly improved on this, finding a way to
pull a block inwards by one diagonal space using 2 gliders, and push
it out the same distance using 3 gliders. In order for the memory to
be of any use there also has to be a way to read the value held. It
suffices to be able to check whether the value is zero (as Conway
did), or to be able to detect the transition from one to zero (as
Hickerson did).
<p>Dean Hickerson's sliding block memory is used in Paul Chapman's
<a href="lex_u.htm#urm">URM</a>, and the key salvos from it are used in several other complex
constructions, such as David Bell's <a href="lex_c.htm#collatz5n1simulator">Collatz 5N+1 simulator</a> and Adam
P. Goucher's <a href="lex_p.htm#picalculator">pi calculator</a> and <a href="#spartan">Spartan</a>
<a href="lex_u.htm#universalcomputer">universal computer</a>-constructor.
<p><a name=slmake>:</a><b>slmake</b> A <a href="#searchprogram">search program</a> published by Adam P. Goucher in May 2017.
It accepts as input a <a href="lex_c.htm#constellation">constellation</a> of sufficiently widely
separated <a href="#stilllife">still lifes</a>, and produces a <a href="lex_g.htm#glider">glider</a> <a href="#stream">stream</a> that will
perform a complete <a href="#slowgliderconstruction">slow glider construction</a> of that constellation,
starting from a single block.
<p>One of slmake's primary uses is to make <a href="#selfconstructing">self-constructing</a>
patterns much easier to design and build. It is capable of finding
<a href="lex_r.htm#recipe">recipes</a> not only for <a href="#spartan">Spartan</a> <a href="#stable">stable</a> <a href="lex_c.htm#circuit">circuitry</a>, but also for
other useful non-Spartan circuits such as <a href="#snark">Snarks</a>, <a href="#syringe">syringes</a>, and
<a href="lex_h.htm#htomwss">H-to-MWSS</a> <a href="lex_c.htm#converter">converters</a>, provided that they are separated from other
nearby objects by a sufficient amount of empty space.
<p><a name=slow>:</a><b>slow</b> See <a href="#slowgliderconstruction">slow glider construction</a>.
<p><a name=slowelbow>:</a><b>slow elbow</b> A movable <a href="lex_c.htm#constructionelbow">construction elbow</a> that is controlled by a
<a href="#slowsalvo">slow salvo</a>, which most likely comes from a previous elbow in a
multi-elbow <a href="lex_c.htm#constructionarm">construction arm</a>. Unlike a standard elbow which is
generally fixed on a single <a href="lex_c.htm#constructionlane">construction lane</a> or at least within a
narrow range, a slow elbow can move freely in two dimensions as long
as there is room for it. Each slow elbow added to a construction arm
results in an exponential increase in the cost (in gliders) of the
final construction. Compare <a href="lex_l.htm#losslesselbow">lossless elbow</a>.
<p><a name=slowgliderconstruction>:</a><b>slow glider construction</b> Construction an object by a "slow salvo" of
<a href="lex_g.htm#glider">gliders</a> all coming from the same direction, in such a way that
timing of the gliders does not matter as long as they are not too
close behind one another. This type of construction requires an
initial seed object, such as a <a href="lex_b.htm#block">block</a>, which is modified by each
glider in turn until the desired object is produced.
<p>In May 1997, Nick Gotts produced a slow glider construction of a
block-laying switch engine from a block, using a slow salvo of 53
gliders. Constructions like this are important in the study of
<a href="#sparselife">sparse Life</a>, as they will occur naturally as gliders created in the
first few generations collide with <a href="lex_b.htm#blonk">blonks</a> and other debris.
<p>Slow glider constructions are also useful in some designs for
<a href="lex_u.htm#universalconstructor">universal constructors</a>. However, in this case the above definition
is usually too restrictive, and it is desirable to allow
constructions in which some gliders in the salvo are required to have
a particular timing modulo 2 (a "p2 slow salvo"). This gives much
greater flexibility, as <a href="lex_b.htm#blinker">blinkers</a> can now be freely used in the
intermediate construction steps. The <a href="#snarkmaker">Snarkmaker</a> is a very large p2
slow salvo. A much smaller example is the following <a href="lex_e.htm#edgy">edgy</a>
construction of an <a href="lex_e.htm#eater1">eater1</a> starting from a block.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO..OOO...............................................$OO..O.................................................$.....O................................................$......................................................$......................................................$......................................................$......................................................$......................................................$......................................................$......................................................$................OOO...................................$................O.....................................$.................O....................................$......................................................$......................................................$......................................................$......................................................$.......................OOO............................$.......................O..............................$........................O.............................$......................................................$......................................................$......................................................$......................................................$......................................................$......................................................$......................................................$..............................O.......................$........................O....OO.......................$.......................OO....O.O......................$.......................O.O............................$......................................................$......................................................$..........................O...........................$.........................OO...........................$.........................O.O..........................$......................................................$.............................OOO....................OO$.............................O.....................OO.$..............................O......................O$"
>OO..OOO...............................................
OO..O.................................................
.....O................................................
......................................................
......................................................
......................................................
......................................................
......................................................
......................................................
......................................................
................OOO...................................
................O.....................................
.................O....................................
......................................................
......................................................
......................................................
......................................................
.......................OOO............................
.......................O..............................
........................O.............................
......................................................
......................................................
......................................................
......................................................
......................................................
......................................................
......................................................
..............................O.......................
........................O....OO.......................
.......................OO....O.O......................
.......................O.O............................
......................................................
......................................................
..........................O...........................
.........................OO...........................
.........................O.O..........................
......................................................
.............................OOO....................OO
.............................O.....................OO.
..............................O......................O
</a></pre></td></tr></table></center>
<p>Adam P. Goucher's <a href="#slmake">slmake</a> <a href="#searchprogram">search program</a>, made available in May
2017, makes it much easier to find a slow glider construction for a
wide variety of <a href="#stable">stable</a> <a href="lex_c.htm#circuit">circuitry</a>.
<p><a name=slowsalvo>:</a><b>slow salvo</b> See <a href="#slowgliderconstruction">slow glider construction</a>.
<p><a name=smallfish>:</a><b>small fish</b> = <a href="lex_l.htm#lwss">LWSS</a>
<p><a name=smalllake>:</a><b>small lake</b> (p1) A 20-cell <a href="#stilllife">still life</a>, but technically not actually
a <a href="lex_l.htm#lake">lake</a> because it is not constructed entirely out of <a href="lex_d.htm#domino">dominoes</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:....O....$...O.O...$...O.O...$.OO...OO.$O.......O$.OO...OO.$...O.O...$...O.O...$....O....$"
>....O....
...O.O...
...O.O...
.OO...OO.
O.......O
.OO...OO.
...O.O...
...O.O...
....O....
</a></pre></td></tr></table></center>
<p><a name=smiley>:</a><b>smiley</b> (p8) Found by Achim Flammenkamp in July 1994 and named by Alan
Hensel.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO.O.OO$...O...$O.....O$.OOOOO.$.......$.......$OOO.OOO$"
>OO.O.OO
...O...
O.....O
.OOOOO.
.......
.......
OOO.OOO
</a></pre></td></tr></table></center>
<p><a name=smmbreeder>:</a><b>SMM breeder</b> See <a href="lex_b.htm#breeder">breeder</a>.
<p><a name=smoke>:</a><b>smoke</b> Debris that is fairly long-lived but eventually dies
completely. Basically, a large <a href="#spark">spark</a>. This term is used
especially when talking about the output from a <a href="#smokingship">smoking ship</a>. Some
<a href="lex_h.htm#herschelconduit">Herschel conduits</a> such as <a href="lex_f.htm#fx119">Fx119</a> also create large amounts of
smoke.
<p><a name=smokingship>:</a><b>smoking ship</b> A <a href="#spaceship">spaceship</a> which produces <a href="#smoke">smoke</a>. If the smoke
extends past the edge of the rest of the spaceship, then it can be
used to perturb other objects as the spaceship passes by. Running
gliders into the smoke is often a good way to turn or duplicate them,
or convert them into other objects. Sometimes the smoke from a
smoking ship may itself be perturbed by accompanying spaceships in
order to form a <a href="lex_p.htm#puffer">puffer</a>. A simple example of a smoking ship is the
<a href="#schickengine">Schick engine</a>.
<p><a name=snacker>:</a><b>snacker</b> (p9) Found by Mark Niemiec in 1972. This is a
<a href="lex_p.htm#pentadecathlon">pentadecathlon</a> with stabilizers which force it into a lower period.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO................OO$.O................O.$.O.O............O.O.$..OO............OO..$.......O....O.......$.....OO.OOOO.OO.....$.......O....O.......$..OO............OO..$.O.O............O.O.$.O................O.$OO................OO$"
>OO................OO
.O................O.
.O.O............O.O.
..OO............OO..
.......O....O.......
.....OO.OOOO.OO.....
.......O....O.......
..OO............OO..
.O.O............O.O.
.O................O.
OO................OO
</a></pre></td></tr></table></center>
The stabilizers make the <a href="lex_d.htm#domino">domino</a> spark largely inaccessible, but the
snacker is <a href="lex_e.htm#extensible">extensible</a>, as shown in the next diagram, and so a more
accessible p9 domino spark can be obtained. In April 1998 Dean
Hickerson found an alternative stabilizer that is less obtrusive than
the original one, and this is also shown in this diagram.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO................................$.O................................$.O.O.........................OO...$..OO.......................O..O...$.......O....O..............OOO....$.....OO.OOOO.OO...O....O......OOO.$.......O....O...OO.OOOO.OO...O...O$..OO..............O....O......OOO.$.O.O.......................OOO....$.O.........................O..O...$OO...........................OO...$"
>OO................................
.O................................
.O.O.........................OO...
..OO.......................O..O...
.......O....O..............OOO....
.....OO.OOOO.OO...O....O......OOO.
.......O....O...OO.OOOO.OO...O...O
..OO..............O....O......OOO.
.O.O.......................OOO....
.O.........................O..O...
OO...........................OO...
</a></pre></td></tr></table></center>
An end can also be stabilized by killer <a href="lex_c.htm#candlefrobra">candlefrobras</a>.
<p><a name=snail>:</a><b>snail</b> (<i>c</i>/5 orthogonally, p5) The first known <a href="lex_c.htm#c5spaceship">c/5 spaceship</a>,
discovered by Tim Coe in January 1996. For some time it was the
slowest known orthogonal spaceship.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.O....................................$.O....................................$O.....................................$.OOO.................OOO...OOO........$.OO.O.........O...O.O......OOO........$..O...........OO.O.......O....OOOO....$......O......O...O.O...OO.O.....OO....$...O..O.OOO...OO.........O........OO.O$...OO.O.....O.....O.................O.$.........O.OOOOOOO....................$......................................$.........O.OOOOOOO....................$...OO.O.....O.....O.................O.$...O..O.OOO...OO.........O........OO.O$......O......O...O.O...OO.O.....OO....$..O...........OO.O.......O....OOOO....$.OO.O.........O...O.O......OOO........$.OOO.................OOO...OOO........$O.....................................$.O....................................$.O....................................$"
>.O....................................
.O....................................
O.....................................
.OOO.................OOO...OOO........
.OO.O.........O...O.O......OOO........
..O...........OO.O.......O....OOOO....
......O......O...O.O...OO.O.....OO....
...O..O.OOO...OO.........O........OO.O
...OO.O.....O.....O.................O.
.........O.OOOOOOO....................
......................................
.........O.OOOOOOO....................
...OO.O.....O.....O.................O.
...O..O.OOO...OO.........O........OO.O
......O......O...O.O...OO.O.....OO....
..O...........OO.O.......O....OOOO....
.OO.O.........O...O.O......OOO........
.OOO.................OOO...OOO........
O.....................................
.O....................................
.O....................................
</a></pre></td></tr></table></center>
<p><a name=snake>:</a><b>snake</b> (p1)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO.O$O.OO$"
>OO.O
O.OO
</a></pre></td></tr></table></center>
<p><a name=snakebit>:</a><b>snake bit</b> An alternative name for a <a href="lex_b.htm#boatbit">boat-bit</a>. Not a very sensible
name, because various other things can be used instead of a snake. A
snake, or alternatively an <a href="lex_a.htm#aircraftcarrier">aircraft carrier</a>, is the smallest object
that can consume a glider <a href="#stream">stream</a> by effectively acting as an
<a href="lex_e.htm#eater">eater</a> for every two incoming gliders. The one-cell reduction from
the smallest real eater, the seven-cell <a href="lex_e.htm#eater1">eater1</a>, has been important
when trying to construct recent <a href="#sawtooth">sawtooths</a> where the <a href="lex_p.htm#population">population</a>
must be minimized.
<p><a name=snakebridgesnake>:</a><b>snake bridge snake</b> (p1)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:....OO$....O.$.....O$....OO$OO.O..$O.OO..$"
>....OO
....O.
.....O
....OO
OO.O..
O.OO..
</a></pre></td></tr></table></center>
<p><a name=snakedance>:</a><b>snake dance</b> (p3) Found by Robert Wainwright, May 1972.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...OO.O..$...O.OO..$OO.O.....$.O..O.OOO$O..O.O..O$OOO.O..O.$.....O.OO$..OO.O...$..O.OO...$"
>...OO.O..
...O.OO..
OO.O.....
.O..O.OOO
O..O.O..O
OOO.O..O.
.....O.OO
..OO.O...
..O.OO...
</a></pre></td></tr></table></center>
<p><a name=snakepit>:</a><b>snake pit</b> This term has been used for two different <a href="lex_o.htm#oscillator">oscillators</a>:
the p2 snake pit (essentially the same as <a href="lex_f.htm#foreandback">fore and back</a>)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:O.OO.OO$OO.O.O.$......O$OOO.OOO$O......$.O.O.OO$OO.OO.O$"
>O.OO.OO
OO.O.O.
......O
OOO.OOO
O......
.O.O.OO
OO.OO.O
</a></pre></td></tr></table></center>
and the p3 snake pit.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.....OO....$....O..O...$....O.OO...$.OO.O......$O.O.O.OOOO.$O.........O$.OOOO.O.O.O$......O.OO.$...OO.O....$...O..O....$....OO.....$"
>.....OO....
....O..O...
....O.OO...
.OO.O......
O.O.O.OOOO.
O.........O
.OOOO.O.O.O
......O.OO.
...OO.O....
...O..O....
....OO.....
</a></pre></td></tr></table></center>
<p><a name=snakesiamesesnake>:</a><b>snake siamese snake</b> (p1)
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO.OO.O$O.OO.OO$"
>OO.OO.O
O.OO.OO
</a></pre></td></tr></table></center>
<p><a name=snark>:</a><b>Snark</b> A small stable 90-degree glider reflector with a repeat time of
43 ticks, discovered by Mike Playle on 25 April 2013 using a search
utility he wrote called <a href="lex_b.htm#bellman">Bellman</a>. Compare <a href="lex_b.htm#boojumreflector">boojum reflector</a>. Four
common Snark variants are shown below: Playle's original at the top,
and variants by Heinrich Koenig, Simon Ekstr&ouml;m, and Shannon Omick to
the left, bottom, and right, respectively. As of June 2018, only
Playle's variant has a known <a href="#slowgliderconstruction">slow glider construction</a> <a href="lex_r.htm#recipe">recipe</a> for
all orientations.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.............................OO....................$............................O.O....................$......................OO....O......................$....................O..O..OO.OOOO..................$....................OO.O.O.O.O..O..................$.......................O.O.O.O.....................$.......................O.O.OO......................$........................O..........................$...................................................$.....................................OO............$............................OO.......O.............$............................OO.....O.O.............$.........O.........................OO..............$.........OOO.......................................$............O........O.............................$...........OO.......O..............................$....................OOO............................$...................................................$...OO..............................................$...O.....................OO........................$OO.O......................O........................$O..OOO....OO...........OOO.........................$.OO...O...OO...........O......................O....$...OOOO.....................OO..............OOOOO..$...O...............OO........O.............O.....O.$....OOO............O.O.......O.O............OOO..O.$.......O.............O........OO...............O.OO$..OOOOO..............OO.....................OOOO..O$.O..O......................O...........OO...O...OO.$.OO......................OOO...........OO....OOO...$........................O......................O...$........................OO.....................O.OO$..............................................OO.OO$...................................................$...................................................$......................................OO...........$......................................O............$.......................................OOO.........$..............OO.........................O.........$.............O.O.....OO............................$.............O.......OO............................$............OO.....................................$...................................................$..........................O........................$................OO....OO.O.O.......................$...............O..O..O.O.O.O.......................$................OO...O.O.O.OO......................$..................OOOO.OO..O.......................$..................O...O....O.......................$...................O..O.OOO........................$....................O.O.O..........................$.....................O.............................$"
>.............................OO....................
............................O.O....................
......................OO....O......................
....................O..O..OO.OOOO..................
....................OO.O.O.O.O..O..................
.......................O.O.O.O.....................
.......................O.O.OO......................
........................O..........................
...................................................
.....................................OO............
............................OO.......O.............
............................OO.....O.O.............
.........O.........................OO..............
.........OOO.......................................
............O........O.............................
...........OO.......O..............................
....................OOO............................
...................................................
...OO..............................................
...O.....................OO........................
OO.O......................O........................
O..OOO....OO...........OOO.........................
.OO...O...OO...........O......................O....
...OOOO.....................OO..............OOOOO..
...O...............OO........O.............O.....O.
....OOO............O.O.......O.O............OOO..O.
.......O.............O........OO...............O.OO
..OOOOO..............OO.....................OOOO..O
.O..O......................O...........OO...O...OO.
.OO......................OOO...........OO....OOO...
........................O......................O...
........................OO.....................O.OO
..............................................OO.OO
...................................................
...................................................
......................................OO...........
......................................O............
.......................................OOO.........
..............OO.........................O.........
.............O.O.....OO............................
.............O.......OO............................
............OO.....................................
...................................................
..........................O........................
................OO....OO.O.O.......................
...............O..O..O.O.O.O.......................
................OO...O.O.O.OO......................
..................OOOO.OO..O.......................
..................O...O....O.......................
...................O..O.OOO........................
....................O.O.O..........................
.....................O.............................
</a></pre></td></tr></table></center>
<p><a name=snarkmaker>:</a><b>Snarkmaker</b> A <a href="#singlechannel">single-channel</a> <a href="#stream">stream</a> of <a href="lex_g.htm#glider">gliders</a> that, when aimed
to collide with an <a href="lex_e.htm#elbow">elbow</a> <a href="lex_b.htm#block">block</a> in a specific location, will
perform a <a href="#slowgliderconstruction">slow glider construction</a> of a <a href="#snark">Snark</a>, directly on the
same <a href="lex_l.htm#lane">lane</a> as the incoming gliders. This allows a
<a href="lex_c.htm#constructionarm">construction arm</a> to add one or more <a href="lex_l.htm#losslesselbow">lossless elbows</a>, so that it
can bend around multiple corners without an exponential increase in
construction cost.
<p>The Snarkmaker recipe used in the first single-channel <a href="lex_d.htm#demonoid">Demonoid</a>,
<a href="lex_o.htm#orthogonoid">Orthogonoid</a>, and <a href="#spiralgrowth">spiral growth</a> patterns contains 2,254 gliders.
This could be considerably reduced with a customized
<a href="#searchprogram">search program</a>.
<p><a name=sng>:</a><b>SNG</b> = <a href="#secondnaturalglider">second natural glider</a>.
<p><a name=sodgame>:</a><b>SODGame</b> = <a href="#seedsofdestructiongame">Seeds of Destruction Game</a>
<p><a name=sombrero>:</a><b>sombrero</b> One half of <a href="#sombreros">sombreros</a> or <a href="#siesta">siesta</a>.
<p><a name=sombreros>:</a><b>sombreros</b> (p6) Found by Dave Buckingham in 1972. If the two halves
are moved three spaces closer to one another then the period drops to
4, and the result is just a less compact form of <a href="lex_a.htm#achimsp4">Achim's p4</a>.
Compare also <a href="#siesta">siesta</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...OO........OO...$...O.O......O.O...$.....O......O.....$...O.OO....OO.O...$.OOO..........OOO.$O...O.O....O.O...O$.OOO..........OOO.$...O.OO....OO.O...$.....O......O.....$...O.O......O.O...$...OO........OO...$"
>...OO........OO...
...O.O......O.O...
.....O......O.....
...O.OO....OO.O...
.OOO..........OOO.
O...O.O....O.O...O
.OOO..........OOO.
...O.OO....OO.O...
.....O......O.....
...O.O......O.O...
...OO........OO...
</a></pre></td></tr></table></center>
<p><a name=soup>:</a><b>soup</b> A random initial pattern, either contained within a small area,
or alternatively filling the whole Life universe.
<p>Finite soups probably have behaviors very different than infinite
soups, but this is obviously unknown. Infinite soups may remain
chaotic indefinitely since any reaction, no matter how rare, is bound
to happen somewhere.
<p>Soups can have an average density, with results varying based on
that. See <a href="#sparselife">sparse Life</a> for a discussion of what can happen at a low
density.
<p>Finite soups for sizes such as 16x16 (asymmetric) have been
examined by the billions by scripts such as <a href="lex_a.htm#apgsearch">apgsearch</a> to find
interesting results. Many new <a href="lex_o.htm#oscillator">oscillators</a> and <a href="#synthesis">synthesis</a>
<a href="lex_r.htm#recipe">recipes</a> have been discovered, as well as previously known rare
patterns such as <a href="#stabilizedswitchengine">stabilized switch engines</a>. In addition, soups are
used to generate statistical <a href="lex_c.htm#census">census</a> data, and to decide whether
specific objects can be considered <a href="lex_n.htm#natural">natural</a>.
<p>Soups can be fully random, or they can be forced to be <a href="#symmetric">symmetric</a>.
The results for these two types of soups can differ since symmetric
soups tend to create large symmetrical objects at a much higher rate.
Shown below is an unusual mirror-symmetric soup that produces a
<a href="lex_p.htm#pufferfish">pufferfish</a> and nothing else.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OOOO..OO.OOO.O...O.OOO.OO..OOOO$.O.O.OO.O.............O.OO.O.O.$..OOO..O.O.O.......O.O.O..OOO..$O.OO.OOO.O..O.....O..O.OOO.OO.O$.OOOO.O...OO.OOOOO.OO...O.OOOO.$.....OO...OO.O.O.O.OO...OO.....$..OOO...OO...O...O...OO...OOO..$O..O..O.OO...OO.OO...OO.O..O..O$OO.O..O...O.........O...O..O.OO$O.O.O...OOOO..OOO..OOOO...O.O.O$O.OOO.OO..OO...O...OO..OO.OOO.O$..O.....OO...O...O...OO.....O..$OOOOO.O.OOO..O...O..OOO.O.OOOOO$.O....O....O..OOO..O....O....O.$.OO.O...OOOOOOOOOOOOOOO...O.OO.$OOOO.OOO......O.O......OOO.OOOO$"
>OOOO..OO.OOO.O...O.OOO.OO..OOOO
.O.O.OO.O.............O.OO.O.O.
..OOO..O.O.O.......O.O.O..OOO..
O.OO.OOO.O..O.....O..O.OOO.OO.O
.OOOO.O...OO.OOOOO.OO...O.OOOO.
.....OO...OO.O.O.O.OO...OO.....
..OOO...OO...O...O...OO...OOO..
O..O..O.OO...OO.OO...OO.O..O..O
OO.O..O...O.........O...O..O.OO
O.O.O...OOOO..OOO..OOOO...O.O.O
O.OOO.OO..OO...O...OO..OO.OOO.O
..O.....OO...O...O...OO.....O..
OOOOO.O.OOO..O...O..OOO.O.OOOOO
.O....O....O..OOO..O....O....O.
.OO.O...OOOOOOOOOOOOOOO...O.OO.
OOOO.OOO......O.O......OOO.OOOO
</a></pre></td></tr></table></center>
<p><a name=spacedust>:</a><b>space dust</b> A part of a <a href="#spaceship">spaceship</a> or <a href="lex_o.htm#oscillator">oscillator</a> which looks like a
random mix of ON and OFF cells. It is usually very difficult to find
a <a href="lex_g.htm#glidersynthesis">glider synthesis</a> for an object that consists wholly or partly of
space dust. As examples, the <a href="lex_1.htm#a-295p5h1v1">295P5H1V1</a>, <a href="lex_f.htm#fly">fly</a>, and <a href="#seal">seal</a>
spaceships contain large amounts of space dust.
<p><a name=spacefiller>:</a><b>spacefiller</b> Any pattern that grows at a quadratic rate by filling
space with an <a href="lex_a.htm#agar">agar</a>. The first example was found in September 1993
by Hartmut Holzwart, following a suggestion by Alan Hensel. The
diagram below shows a smaller spacefiller found by Tim Coe. See also
<a href="lex_m.htm#max">Max</a>. Spacefillers can be considered as <a href="lex_b.htm#breeder">breeders</a> (more precisely,
MMS breeders), but they are very different from ordinary breeders.
The word "spacefiller" was suggested by Harold McIntosh and soon
became the accepted term.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..................O........$.................OOO.......$............OOO....OO......$...........O..OOO..O.OO....$..........O...O.O..O.O.....$..........O....O.O.O.O.OO..$............O....O.O...OO..$OOOO.....O.O....O...O.OOO..$O...OO.O.OOO.OO.........OO.$O.....OO.....O.............$.O..OO.O..O..O.OO..........$.......O.O.O.O.O.O.....OOOO$.O..OO.O..O..O..OO.O.OO...O$O.....OO...O.O.O...OO.....O$O...OO.O.OO..O..O..O.OO..O.$OOOO.....O.O.O.O.O.O.......$..........OO.O..O..O.OO..O.$.............O.....OO.....O$.OO.........OO.OOO.O.OO...O$..OOO.O...O....O.O.....OOOO$..OO...O.O....O............$..OO.O.O.O.O....O..........$.....O.O..O.O...O..........$....OO.O..OOO..O...........$......OO....OOO............$.......OOO.................$........O..................$"
>..................O........
.................OOO.......
............OOO....OO......
...........O..OOO..O.OO....
..........O...O.O..O.O.....
..........O....O.O.O.O.OO..
............O....O.O...OO..
OOOO.....O.O....O...O.OOO..
O...OO.O.OOO.OO.........OO.
O.....OO.....O.............
.O..OO.O..O..O.OO..........
.......O.O.O.O.O.O.....OOOO
.O..OO.O..O..O..OO.O.OO...O
O.....OO...O.O.O...OO.....O
O...OO.O.OO..O..O..O.OO..O.
OOOO.....O.O.O.O.O.O.......
..........OO.O..O..O.OO..O.
.............O.....OO.....O
.OO.........OO.OOO.O.OO...O
..OOO.O...O....O.O.....OOOO
..OO...O.O....O............
..OO.O.O.O.O....O..........
.....O.O..O.O...O..........
....OO.O..OOO..O...........
......OO....OOO............
.......OOO.................
........O..................
</a></pre></td></tr></table></center>
<p><a name=spacenonfiller>:</a><b>space nonfiller</b> Any pattern that expands indefinitely to affect every
cell in the Life plane, but leaves an expanding region of <a href="lex_v.htm#vacuum">vacuum</a> at
its center. Compare <a href="#spacefiller">spacefiller</a>; see also <a href="lex_a.htm#antstretcher">antstretcher</a>. The
first nonfiller was discovered by Jason Summers on 14 April 1999:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...................OOO...............$..................O..O...............$............OOO......O....OOO........$............O..O.O...O....O..O.......$............O..O.O...O....O..O.......$..........O..........O..O.O.OOO......$..........OO..OO..O.O....O.....O.....$........O................OO..OOO.....$........OOO.O.OO..........O......O...$......O........O.........O.O...OOO...$......OOO.....O..........O........O..$...O.O.........................O.OOO.$..OOOOO.O..........................O.$.OO......O.....................OOOOO.$OO....OO..................O.O........$.O.O...O..O...............O..O...O.O.$........O.O..................OO....OO$.OOOOO.....................O......OO.$.O..........................O.OOOOO..$.OOO.O.........................O.O...$..O........O..........O.....OOO......$...OOO...O.O.........O........O......$...O......O..........OO.O.OOO........$.....OOO..OO................O........$.....O.....O....O.O..OO..OO..........$......OOO.O.O..O..........O..........$.......O..O....O...O.O..O............$.......O..O....O...O.O..O............$........OOO....O......OOO............$...............O..O..................$...............OOO...................$"
>...................OOO...............
..................O..O...............
............OOO......O....OOO........
............O..O.O...O....O..O.......
............O..O.O...O....O..O.......
..........O..........O..O.O.OOO......
..........OO..OO..O.O....O.....O.....
........O................OO..OOO.....
........OOO.O.OO..........O......O...
......O........O.........O.O...OOO...
......OOO.....O..........O........O..
...O.O.........................O.OOO.
..OOOOO.O..........................O.
.OO......O.....................OOOOO.
OO....OO..................O.O........
.O.O...O..O...............O..O...O.O.
........O.O..................OO....OO
.OOOOO.....................O......OO.
.O..........................O.OOOOO..
.OOO.O.........................O.O...
..O........O..........O.....OOO......
...OOO...O.O.........O........O......
...O......O..........OO.O.OOO........
.....OOO..OO................O........
.....O.....O....O.O..OO..OO..........
......OOO.O.O..O..........O..........
.......O..O....O...O.O..O............
.......O..O....O...O.O..O............
........OOO....O......OOO............
...............O..O..................
...............OOO...................
</a></pre></td></tr></table></center>
<p><a name=spacerake>:</a><b>space rake</b> The following p20 forwards glider <a href="lex_r.htm#rake">rake</a>, which was the
first known rake. It consists of an <a href="lex_e.htm#ecologist">ecologist</a> with a <a href="lex_l.htm#lwss">LWSS</a> added
to turn the dying debris into <a href="lex_g.htm#glider">gliders</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...........OO.....OOOO$.........OO.OO...O...O$.........OOOO........O$..........OO.....O..O.$......................$........O.............$.......OO........OO...$......O.........O..O..$.......OOOOO....O..O..$........OOOO...OO.OO..$...........O....OO....$......................$......................$......................$..................OOOO$O..O.............O...O$....O................O$O...O............O..O.$.OOOO.................$"
>...........OO.....OOOO
.........OO.OO...O...O
.........OOOO........O
..........OO.....O..O.
......................
........O.............
.......OO........OO...
......O.........O..O..
.......OOOOO....O..O..
........OOOO...OO.OO..
...........O....OO....
......................
......................
......................
..................OOOO
O..O.............O...O
....O................O
O...O............O..O.
.OOOO.................
</a></pre></td></tr></table></center>
<p><a name=spaceship>:</a><b>spaceship</b> Any finite pattern that reappears (without additions or
losses) after a number of generations and displaced by a non-zero
amount. By far the most <a href="lex_n.htm#natural">natural</a> spaceships are the <a href="lex_g.htm#glider">glider</a>,
<a href="lex_l.htm#lwss">LWSS</a>, <a href="lex_m.htm#mwss">MWSS</a> and <a href="lex_h.htm#hwss">HWSS</a>, followed by the <a href="lex_c.htm#coeship">Coe ship</a> which has also
evolved multiple times from random asymmetric <a href="#soup">soup</a> starting
conditions. See also the entries on individual spaceship speeds:
<a href="lex_c.htm#c2spaceship">c/2 spaceship</a>, <a href="lex_c.htm#c3spaceship">c/3 spaceship</a>, <a href="lex_c.htm#c4spaceship">c/4 spaceship</a>, <a href="lex_c.htm#c5spaceship">c/5 spaceship</a>,
<a href="lex_c.htm#c6spaceship">c/6 spaceship</a>, <a href="lex_c.htm#c7spaceship">c/7 spaceship</a>, <a href="lex_c.htm#c10spaceship">c/10 spaceship</a>, <a href="lex_c.htm#c12spaceship">c/12 spaceship</a>,
<a href="lex_1.htm#a-2c5spaceship">2c/5 spaceship</a>, <a href="lex_1.htm#a-2c7spaceship">2c/7 spaceship</a>, <a href="lex_1.htm#a-3c7spaceship">3c/7 spaceship</a>,
<a href="lex_1.htm#a-21c6spaceship">(2,1)c/6 spaceship</a>, and <a href="lex_1.htm#a-17c45spaceship">17c/45 spaceship</a>.
<p>It is known that there exist spaceships travelling in all rational
directions and at arbitrarily slow speeds (see
<a href="lex_u.htm#universalconstructor">universal constructor</a>). Before 1989, however, the only known
examples travelled at <i>c</i>/4 diagonally (gliders) or <i>c</i>/2 orthogonally
(everything else).
<p>In 1989 Dean Hickerson started to use automated searches to look
for new <a href="lex_e.htm#elementary">elementary</a> spaceships, and had considerable success. Other
people have continued these searches using tools such as <a href="lex_l.htm#lifesrc">lifesrc</a>
and <a href="lex_g.htm#gfind">gfind</a>, and as a result we now have a great variety of
elementary spaceships travelling at sixteen different velocities.
The following table details the discovery of elementary spaceships
with new velocities as of July 2018.
<pre>
  -----------------------------------------------------------------
  Speed    Direction  First Discovery   Discoverer             Date
  -----------------------------------------------------------------
  c/4      diagonal   <a href="lex_g.htm#glider">glider</a>            Richard Guy            1970
  c/2      orthogonal <a href="lex_l.htm#lwss">LWSS</a>              John Conway            1970
  c/3      orthogonal <a href="lex_1.htm#a-25p3h1v01">25P3H1V0.1</a>        Dean Hickerson     Aug 1989
  c/4      orthogonal <a href="lex_1.htm#a-119p4h1v0">119P4H1V0</a>         Dean Hickerson     Dec 1989
  c/12     diagonal   <a href="lex_c.htm#cordership">Cordership</a>        Dean Hickerson     Apr 1991
  2c/5     orthogonal <a href="lex_1.htm#a-44p5h2v0">44P5H2V0</a>          Dean Hickerson     Jul 1991
  c/5      orthogonal <a href="lex_s.htm#snail">snail</a>             Tim Coe            Jan 1996
  2c/7     orthogonal <a href="lex_w.htm#weekender">weekender</a>         David Eppstein     Jan 2000
  c/6      orthogonal <a href="lex_d.htm#dragon">dragon</a>            Paul Tooke         Apr 2000
  c/5      diagonal   <a href="lex_1.htm#a-295p5h1v1">295P5H1V1</a>         Jason Summers      Nov 2000
  c/6      diagonal   <a href="lex_s.htm#seal">seal</a>              Nicolay Beluchenko Sep 2005
  c/7      diagonal   <a href="lex_l.htm#lobster">lobster</a>           Matthias Merzenich Aug 2011
  c/7      orthogonal <a href="lex_l.htm#loafer">loafer</a>            Josh Ball          Feb 2013
  c/10     orthogonal <a href="lex_c.htm#copperhead">copperhead</a>        zdr                Mar 2016
  3c/7     orthogonal <a href="lex_s.htm#spaghettimonster">spaghetti monster</a> Tim Coe            Jun 2016
  (2,1)c/7 oblique    <a href="lex_s.htm#sirrobin">Sir Robin</a>         Adam P. Goucher    Mar 2018
  -----------------------------------------------------------------
</pre>
<p>Several infinite families of adjustable-velocity <a href="lex_m.htm#macrospaceship">macro-spaceships</a>
have also been constructed, of which the first was Gabriel Nivasch's
<a href="lex_c.htm#caterpillar">Caterpillar</a> from December 2004. The macro-spaceship with the
widest range of possible speeds is Michael Simkin's <a href="lex_c.htm#caterloopillar">Caterloopillar</a>
from April 2016; in theory it supports any rational orthogonal speed
strictly less than <i>c</i>&lt;4. A somewhat similar design supporting any
rational speed strictly less than <i>c</i>/2 has been shown to be feasible,
but as of July 2018 no explicit examples have been constructed.
<p>A period <i>p</i> spaceship that displaces itself (<i>m</i>,<i>n</i>) during its period,
where <i>m</i>&gt;=<i>n</i>, is said to be of type (<i>m</i>,<i>n</i>)/<i>p</i>. It was proved by Conway
in 1970 that <i>p</i>&gt;=2<i>m</i>+2<i>n</i>. (This follows immediately from the
easily-proved fact that a pattern cannot advance diagonally at a rate
greater than one half diagonal step every other generation.)
<p><a name=spaceshipsinconwayslife>:</a><b>Spaceships in Conway's Life</b> A series of articles posted by David Bell
to the newsgroup comp.theory.cell-automata during the period
August-October 1992 that described many of the new <a href="#spaceship">spaceships</a> found
by himself, Dean Hickerson and Hartmut Holzwart. Bell produced an
addendum covering more recent developments in 1996.
<p><a name=spaghettimonster>:</a><b>spaghetti monster</b> The first <a href="lex_1.htm#a-3c7spaceship">3c/7 spaceship</a>, found by Tim Coe in
June 2016. The spaceship travels orthogonally, has a minimum of 702
live cells and fits in a 27x137 bounding box.
<p><a name=spark>:</a><b>spark</b> A pattern that dies. The term is typically used to describe a
collection of cells periodically thrown off by an <a href="lex_o.htm#oscillator">oscillator</a> or
<a href="#spaceship">spaceship</a>, but other dying patterns, particularly those consisting
or only one or two cells (such as produced by certain glider
collisions, for example), are also described as sparks. For examples
of small sparks see <a href="lex_u.htm#unix">unix</a> and <a href="lex_h.htm#hwss">HWSS</a>. Examples of much larger
sparks are seen in <a href="#schickengine">Schick engine</a> and <a href="lex_t.htm#twinbeesshuttlespark">twin bees shuttle spark</a>.
<p><a name=sparkcoil>:</a><b>spark coil</b> (p2) Found in 1971.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO....OO$O.O..O.O$..O..O..$O.O..O.O$OO....OO$"
>OO....OO
O.O..O.O
..O..O..
O.O..O.O
OO....OO
</a></pre></td></tr></table></center>
<p><a name=sparker>:</a><b>sparker</b> An <a href="lex_o.htm#oscillator">oscillator</a> or <a href="#spaceship">spaceship</a> that produces <a href="#spark">sparks</a>. These
can be used to <a href="lex_p.htm#perturb">perturb</a> other patterns without being themselves
affected.
<p><a name=sparkingeater>:</a><b>sparking eater</b> One of two <a href="lex_e.htm#eater">eaters</a> found in April 1997 and November
1998 by Dean Hickerson using his <a href="lex_d.htm#dr">dr</a> <a href="#searchprogram">search program</a>, shown below
to the left and right respectively. These both absorb <a href="lex_g.htm#glider">gliders</a> as a
standard eater does, but also produce separated single-bit <a href="#spark">sparks</a>
at the upper right, which can be used to delete antiparallel gliders
with different phases as shown.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..O.........OO........O..........OO.$O.O........OO.......O.O..........O.O$.OO..........O.......OO..........O..$....OO..OO...............OO..OO.....$.O...O..OO............O...O..OO.....$.OOOO.............OO..OOOO..........$..................O.................$.OO................OOOOO............$.OO.....................O...........$.....................OOO............$.....................O..............$"
>..O.........OO........O..........OO.
O.O........OO.......O.O..........O.O
.OO..........O.......OO..........O..
....OO..OO...............OO..OO.....
.O...O..OO............O...O..OO.....
.OOOO.............OO..OOOO..........
..................O.................
.OO................OOOOO............
.OO.....................O...........
.....................OOO............
.....................O..............
</a></pre></td></tr></table></center>
The above mechanisms can be used to build <a href="lex_i.htm#intermittingglidergun">intermitting glider guns</a>.
The left-hand eater produces a spark nine ticks after a glider
impact, with the result that the period of the constituent guns can't
be a multiple of 4. The right-hand eater produces the same spark ten
ticks after impact, which allows p4<i>N</i> guns to be used.
<p>The separation of the spark also allows this reaction to perform
other <a href="lex_p.htm#perturbation">perturbations</a> "around the corner" of some objects. For
example, it was used by Jason Summers in 2004 to cap the ends of a
row of ten <a href="lex_a.htm#ak47reaction">AK47 reactions</a> to form a much smaller period 94 glider
gun than the original one. (This is now made obsolete by the
<a href="lex_a.htm#ak94gun">AK94 gun</a>.)
<p><a name=sparky>:</a><b>sparky</b> A certain <i>c</i>/4 <a href="lex_t.htm#tagalong">tagalong</a>, shown here attached to the back of a
<a href="#spaceship">spaceship</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..........O....................$..........O...............OO...$......OO.O.OOO..........OO...O.$O.OO.OO.OO..O.O...OO.OOOO......$O...OO..O.OO..OOO..O.OO..OO...O$O.OO....OOO.O.OOO......OO..O...$........OO.O...............O..O$O.OO....OOO.O.OOO......OO..O...$O...OO..O.OO..OOO..O.OO..OO...O$O.OO.OO.OO..O.O...OO.OOOO......$......OO.O.OOO..........OO...O.$..........O...............OO...$..........O....................$"
>..........O....................
..........O...............OO...
......OO.O.OOO..........OO...O.
O.OO.OO.OO..O.O...OO.OOOO......
O...OO..O.OO..OOO..O.OO..OO...O
O.OO....OOO.O.OOO......OO..O...
........OO.O...............O..O
O.OO....OOO.O.OOO......OO..O...
O...OO..O.OO..OOO..O.OO..OO...O
O.OO.OO.OO..O.O...OO.OOOO......
......OO.O.OOO..........OO...O.
..........O...............OO...
..........O....................
</a></pre></td></tr></table></center>
<p><a name=sparselife>:</a><b>sparse Life</b> This refers to the study of the evolution of a Life
universe which starts off as a random <a href="#soup">soup</a> of extremely low
density. Such a universe is dominated at an early stage by <a href="lex_b.htm#block">blocks</a>
and <a href="lex_b.htm#blinker">blinkers</a> (often referred to collectively as <a href="lex_b.htm#blonk">blonks</a>) in a
ratio of about 2:1. Much later it will be dominated by simple
<a href="lex_i.htm#infinitegrowth">infinite growth</a> patterns (presumably mostly <a href="#switchengine">switch engines</a>). The
long-term fate of a sparse Life universe is less certain. It may
possibly become dominated by self-reproducing patterns (see
<a href="lex_u.htm#universalconstructor">universal constructor</a>), but it is not at all clear that there is
any mechanism for these to deal with all the junk produced by switch
engines.
<p><a name=spartan>:</a><b>Spartan</b> A pattern composed of subunits that can be easily constructed
in any orientation, usually with a <a href="#slowsalvo">slow salvo</a>. Generally this means
that the pattern is a <a href="lex_c.htm#constellation">constellation</a> of Spartan still lifes:
<a href="lex_b.htm#block">block</a>, <a href="lex_t.htm#tub">tub</a>, <a href="lex_b.htm#boat">boat</a>, <a href="lex_h.htm#hive">hive</a>, <a href="#ship">ship</a>, <a href="lex_l.htm#loaf">loaf</a>, <a href="lex_e.htm#eater1">eater1</a>, or <a href="lex_p.htm#pond">pond</a>.
Other small objects may sometimes be counted as Spartan, including
period-2 oscillators - mainly <a href="lex_b.htm#blinker">blinkers</a>, but also <a href="lex_b.htm#beacon">beacons</a> or
<a href="lex_t.htm#toad">toads</a>, which may occur as <a href="lex_i.htm#intermediatetarget">intermediate targets</a> in slow salvo
<a href="lex_r.htm#recipe">recipes</a>. Most <a href="#selfconstructing">self-constructing</a> patterns are Spartan or mostly
Spartan, to simplify the process of self-construction.
<p><a name=speedbooster>:</a><b>speed booster</b> Any mechanism which allows a <a href="#signal">signal</a> (indicated by the
presence or absence of a spaceship) to move faster than the spaceship
could travel through empty space. The original speed booster is
based on p30 <a href="lex_t.htm#technology">technology</a>, and is shown below:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:....................O........................$.....................O.......................$...................OOO.......................$.............................................$...........................O.O...............$.........................O...O...............$.................O.......O...................$................OOOO....O....O........OO.....$...............OO.O.O....O............OO.....$....OO........OOO.O..O...O...O...............$....OO.........OO.O.O......O.O...............$................OOOO.........................$.................O...........................$..........................OOO................$..........................O.O...OO...........$.........................OO.....O..O.........$..................O.O.....O.........O......OO$................O...O..OO...........O......OO$.........OO.....O..........O........O........$.O.......OO....O....O.......OO..O..O.........$..O.............O.......O.O..O..OO...........$OOO.............O...O.....OOO................$..................O.O........................$"
>....................O........................
.....................O.......................
...................OOO.......................
.............................................
...........................O.O...............
.........................O...O...............
.................O.......O...................
................OOOO....O....O........OO.....
...............OO.O.O....O............OO.....
....OO........OOO.O..O...O...O...............
....OO.........OO.O.O......O.O...............
................OOOO.........................
.................O...........................
..........................OOO................
..........................O.O...OO...........
.........................OO.....O..O.........
..................O.O.....O.........O......OO
................O...O..OO...........O......OO
.........OO.....O..........O........O........
.O.......OO....O....O.......OO..O..O.........
..O.............O.......O.O..O..OO...........
OOO.............O...O.....OOO................
..................O.O........................
</a></pre></td></tr></table></center>
Here the top glider is boosted by passing through two
<a href="lex_i.htm#inlineinverter">inline inverters</a>, emerging 5 cells further along than the unboosted
glider at the left.
<p>The fastest speed boosters are the <a href="lex_t.htm#telegraph">telegraph</a> and <a href="lex_p.htm#p1telegraph">p1 telegraph</a>,
which can transfer a orthogonal signal at the <a href="#speedoflight">speed of light</a>,
although their bit rate is rather slow.
<p>Diagonal speed boosters have also been built using <a href="lex_1.htm#a-2c3wire">2c/3 wires</a> or
other stable components. See <a href="#stablepseudoheisenburp">stable pseudo-Heisenburp</a>.
<p>The <a href="#stargate">star gate</a> seems like it can transfer a signal faster than the
<a href="#speedoflight">speed of light</a>. The illusion is explained in
<a href="lex_f.htm#fastforwardforcefield">Fast Forward Force Field</a>.
<p><a name=speedoflight>:</a><b>speed of light</b> The greatest speed at which any effect can propagate;
in <a href="lex_l.htm#life">Life</a>, a speed of one cell per <a href="lex_g.htm#generation">generation</a>. Usually denoted <i>c</i>.
<p><a name=spentomino>:</a><b>S-pentomino</b> Conway's name for the following <a href="lex_p.htm#pentomino">pentomino</a>, which
rapidly dies.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..OO$OOO.$"
>..OO
OOO.
</a></pre></td></tr></table></center>
<p><a name=spider>:</a><b>spider</b> (<i>c</i>/5 orthogonally, p5) This is the smallest known <i>c</i>/5
<a href="#spaceship">spaceship</a>, and was found by David Bell in April 1997. Its side
<a href="#spark">sparks</a> have proved very useful in constructing <i>c</i>/5 <a href="lex_p.htm#puffer">puffers</a>,
including <a href="lex_r.htm#rake">rakes</a>. See also <a href="lex_p.htm#pps">PPS</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:......O...OOO.....OOO...O......$...OO.OOOOO.OO...OO.OOOOO.OO...$.O.OO.O.....O.O.O.O.....O.OO.O.$O...O.O...OOOOO.OOOOO...O.O...O$....OOO.....OO...OO.....OOO....$.O..O.OOO.............OOO.O..O.$...O.......................O...$"
>......O...OOO.....OOO...O......
...OO.OOOOO.OO...OO.OOOOO.OO...
.O.OO.O.....O.O.O.O.....O.OO.O.
O...O.O...OOOOO.OOOOO...O.O...O
....OOO.....OO...OO.....OOO....
.O..O.OOO.............OOO.O..O.
...O.......................O...
</a></pre></td></tr></table></center>
<p><a name=spiral>:</a><b>spiral</b> (p1) Found by Robert Wainwright in 1971.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO....O$.O..OOO$.O.O...$..O.O..$...O.O.$OOO..O.$O....OO$"
>OO....O
.O..OOO
.O.O...
..O.O..
...O.O.
OOO..O.
O....OO
</a></pre></td></tr></table></center>
<p><a name=spiralgrowth>:</a><b>spiral growth</b> A <a href="#selfconstructing">self-constructing</a> pattern built by Dave Greene in
August 2014 that uses four <a href="lex_u.htm#universalconstructor">universal constructors</a> (UCs) arranged in
a diamond to build four more UCs in a slightly larger diamond. This
was the first B3/S23 pattern that exhibited spiral growth. Much
smaller versions have now been constructed using the <a href="#singlechannel">single-channel</a>
construction toolkit.
<p><a name=splitter>:</a><b>splitter</b> A <a href="#signal">signal</a> <a href="lex_c.htm#converter">converter</a> that accepts a single input signal
and produces two or more output signals, usually of the same type as
the input. An older term for this is <a href="lex_f.htm#fanout">fanout</a>, or "fanout device".
<p>A sub-category is the <a href="lex_o.htm#onetime">one-time</a> splitter, which is not technically
a converter because it can only be used once. One-time splitters are
usually small <a href="lex_c.htm#constellation">constellations</a> that produce two or more <a href="lex_c.htm#clean">clean</a>
gliders when struck by a single glider. In other words, they are
multi-glider <a href="#seed">seeds</a>. These are important for constructing
self-destruct circuitry in <a href="#selfconstructing">self-constructing</a> spaceships.
<p>The following combination, a <a href="#syringe">syringe</a> attached to an SE7T14
<a href="lex_c.htm#converter">converter</a> combined with an <a href="lex_n.htm#nw31">NW31</a> converter, is one of the smallest
known glider splitters as of July 2018. Another small splitter with
a 90-degree <a href="lex_c.htm#colourchanging">colour-changing</a> output is shown under <a href="lex_r.htm#reflector">reflector</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..........OO...........O......OO....................$..........OO..........O.O....O..O...................$......................O.O...O.OOO...O...............$.....................OO.OO.O.O......OOO.............$.........................O.O...OO......O............$.....................OO.O..OOOO.O.....OO............$.....................OO.O.O...O.....................$.........................O.O...O....................$..........................O.O...O...................$...........................O...OO...................$....................................................$....................................................$....................................................$..................OO................................$..................OO................................$...OO...............................................$..O..O..............................................$.O.OO...............................................$.O................................................OO$OO................................................OO$...............OO...................................$...............O....................................$................OOO.................................$..................O..........OO.....................$............................O.O.....................$............................O.......................$...........................OO.......................$OOO.................................................$..O.................................................$.O..................................................$"
>..........OO...........O......OO....................
..........OO..........O.O....O..O...................
......................O.O...O.OOO...O...............
.....................OO.OO.O.O......OOO.............
.........................O.O...OO......O............
.....................OO.O..OOOO.O.....OO............
.....................OO.O.O...O.....................
.........................O.O...O....................
..........................O.O...O...................
...........................O...OO...................
....................................................
....................................................
....................................................
..................OO................................
..................OO................................
...OO...............................................
..O..O..............................................
.O.OO...............................................
.O................................................OO
OO................................................OO
...............OO...................................
...............O....................................
................OOO.................................
..................O..........OO.....................
............................O.O.....................
............................O.......................
...........................OO.......................
OOO.................................................
..O.................................................
.O..................................................
</a></pre></td></tr></table></center>
<p><a name=spps>:</a><b>SPPS</b> (<i>c</i>/5 orthogonally, p30) The symmetric <a href="lex_p.htm#pps">PPS</a>. The original PPS
found by David Bell in May 1998. Compare <a href="lex_a.htm#apps">APPS</a>.
<p><a name=sqrtgun>:</a><b>sqrtgun</b> Any glider-emitting pattern which emits its nth glider at a
time asymptotically proportional to <i>n</i><sup>2</sup>. The first examples were
constructed by Dean Hickerson around 1991. See also
<a href="lex_q.htm#quadraticfilter">quadratic filter</a>, <a href="lex_e.htm#exponentialfilter">exponential filter</a>, <a href="lex_r.htm#recursivefilter">recursive filter</a>.
<p><a name=squaredance>:</a><b>squaredance</b> The p2 <a href="lex_a.htm#agar">agar</a> formed by tiling the plane with the
following pattern. Found by Don Woods in 1971.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OO......$....OO..$..O....O$..O....O$....OO..$OO......$...O..O.$...O..O.$"
>OO......
....OO..
..O....O
..O....O
....OO..
OO......
...O..O.
...O..O.
</a></pre></td></tr></table></center>
<p><a name=squirter>:</a><b>squirter</b> = <a href="lex_p.htm#pipsquirter">pipsquirter</a>
<p><a name=sspiral>:</a><b>S-spiral</b> = <a href="lex_b.htm#bigs">big S</a>
<p><a name=stabilizedswitchengine>:</a><b>stabilized switch engine</b> A single <a href="#switchengine">switch engine</a> which survives
indefinitely by interacting with the appropriate <a href="lex_e.htm#exhaust">exhaust</a> such that
it prevents the engine from ever being destroyed.
<p>The only known types of stabilized switch engines were found by
Charles Corderman soon after he discovered the switch engine itself.
There is a p288 block-laying type (the more common of the two) and
the p384 glider-producing type. These two puffers are the most
<a href="lex_n.htm#natural">natural</a> infinite growth patterns in Life. As of June 2018 they are
the basis for every infinite growth pattern ever seen to occur from a
random asymmetric <a href="#soup">soup</a>, even after trillions of <a href="lex_c.htm#census">census</a> results by
<a href="lex_a.htm#apgsearch">apgsearch</a> and similar projects.
<p>Patterns giving rise to block-laying switch engines can be seen
under <a href="lex_i.htm#infinitegrowth">infinite growth</a>, and one giving rise to a glider-producing
switch engine is shown under <a href="lex_t.htm#timebomb">time bomb</a>.
<p>Here is the block-laying type showing its distinctive zig-zag trail
of blocks.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..O.........................................................$.O.O........................................................$............................................................$.O..O.......................................................$...OO.......................................................$....O.......................................................$..................OO........................................$..................OO........................................$............................................................$............................................................$.OO.........................................................$...O........................................................$..OO........................................................$.OOO...............O........................................$.OO................OO.....OO................................$OOO.O..............OO.....OO................................$.O...O..........OO..........................................$...O..O..........O..........................................$...OOO............O.........................................$....OO........OO............................................$..............OO............................................$............................................................$..................................OO........................$..................................OO........................$............................................................$............................................................$......OO....................................................$......OO................OO..................................$........................OO..................................$............................................................$..........................................OO................$....................OO....................OO................$....................OO......................................$............................................................$..............OO............................................$..............OO............................................$.......................................OO...................$.......................................OO...................$............................................................$............................................................$...................................OO.......................$...................................OO.......................$............................................................$............................................................$............................................................$............................................................$..........................................................OO$..........................................................OO$............................................................$............................................................$..............................OO............................$..............................OO................OO..........$................................................OO..........$............................................................$............................................................$............................................OO..............$............................................OO..............$............................................................$......................................OO....................$......................................OO....................$"
>..O.........................................................
.O.O........................................................
............................................................
.O..O.......................................................
...OO.......................................................
....O.......................................................
..................OO........................................
..................OO........................................
............................................................
............................................................
.OO.........................................................
...O........................................................
..OO........................................................
.OOO...............O........................................
.OO................OO.....OO................................
OOO.O..............OO.....OO................................
.O...O..........OO..........................................
...O..O..........O..........................................
...OOO............O.........................................
....OO........OO............................................
..............OO............................................
............................................................
..................................OO........................
..................................OO........................
............................................................
............................................................
......OO....................................................
......OO................OO..................................
........................OO..................................
............................................................
..........................................OO................
....................OO....................OO................
....................OO......................................
............................................................
..............OO............................................
..............OO............................................
.......................................OO...................
.......................................OO...................
............................................................
............................................................
...................................OO.......................
...................................OO.......................
............................................................
............................................................
............................................................
............................................................
..........................................................OO
..........................................................OO
............................................................
............................................................
..............................OO............................
..............................OO................OO..........
................................................OO..........
............................................................
............................................................
............................................OO..............
............................................OO..............
............................................................
......................................OO....................
......................................OO....................
</a></pre></td></tr></table></center>
<p><a name=stable>:</a><b>stable</b> A pattern is said to be stable if it is a <a href="lex_p.htm#parent">parent</a> of itself.
Stable objects are oscillators with period 1 (p1), and are generally
called <a href="#stilllife">still lifes</a>.
<p><a name=stablepseudoheisenburp>:</a><b>stable pseudo-Heisenburp</b> A multi-stage <a href="lex_c.htm#converter">converter</a> constructed by
Dave Greene in January 2007, using a complex recipe found by Noam
Elkies to insert a signal into a <a href="lex_1.htm#a-2c3wire">2c/3 wire</a>. The wire's high
transmission speed allows a <a href="#signal">signal</a> from a <a href="lex_h.htm#highwayrobber">highway robber</a> to catch
up to a <a href="#salvo">salvo</a> of <a href="lex_g.htm#glider">gliders</a>. Ultimately the mechanism restores the
key glider, which was destroyed by the highway robber in the first
stage of the converter, to its exact original position in the salvo.
<p>Much smaller stable pseudo-Heisenburp devices have since been
designed that use simple 0-degree glider <a href="#seed">seed</a> <a href="lex_c.htm#constellation">constellations</a>
instead of a 2<i>c</i>/3 wire.
<p>These patterns are labeled "pseudo-Heisenburp", because a true
<a href="lex_h.htm#heisenburpdevice">Heisenburp device</a> does not even temporarily damage or affect a
passing glider, yet can still produce an output <a href="#signal">signal</a> in response.
However, it is impossible to construct a <a href="#stable">stable</a> device that can
accomplish this for gliders. True stable Heisenburp devices are
possible with many other types of <a href="#spaceship">spaceships</a>, but not with gliders
which have no usable side <a href="#spark">sparks</a> to initiate an output signal.
<p><a name=stagedrecovery>:</a><b>staged recovery</b> A type of signal-processing <a href="lex_c.htm#circuit">circuit</a> where the
initial reaction between <a href="lex_c.htm#catalyst">catalysts</a> an incoming signal results in an
imperfect recovery. A catalyst is damaged, destroyed completely as
in a <a href="lex_b.htm#bait">bait</a> reaction, or one or more objects are left behind that
must be cleaned up before the circuit can be reused. In any of these
three cases, output signals from the circuit must be used to complete
the cleanup. In theory the cleanup process might itself be <a href="lex_d.htm#dirty">dirty</a>,
requiring additional cleanup stages. In rare cases this might
theoretically allow the construction of special-purpose circuits with
a lower <a href="lex_r.htm#recoverytime">recovery time</a> than would otherwise be possible, but in
practice this kind of situation does not commonly arise.
<p>An example is the record-breaking (at the time) 487-tick reflector
constructed by Adam P. Goucher on 12 April 2009. 487 ticks was a
slight improvement over the repeat time of the <a href="#silverreflector">Silver reflector</a>.
The reflector featured a standard <a href="lex_c.htm#callahangtoh">Callahan G-to-H</a>, with cleanup by
an internal <a href="lex_d.htm#dirty">dirty</a> glider reflector found by Dieter Leithner many
years before. This in turn was cleaned up by the usual ungainly
Herschel plumbing attached to the G-to-H's output. The dirty glider
reflector is not actually fully recovered before a second p487 signal
enters the full reflector. However, it has been repaired by the time
the internal reflector is actually needed again, so the cycle can be
successfully repeated at p487 instead of p497.
<p><a name=stairstephexomino>:</a><b>stairstep hexomino</b> (stabilizes at time 63) The following
<a href="lex_p.htm#predecessor">predecessor</a> of the <a href="lex_b.htm#blockade">blockade</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..OO$.OO.$OO..$"
>..OO
.OO.
OO..
</a></pre></td></tr></table></center>
<p><a name=stampcollection>:</a><b>stamp collection</b> A collection of <a href="lex_o.htm#oscillator">oscillators</a> (or perhaps other Life
objects) in a single diagram, displaying the exhibits much like
stamps in a stamp album. The classic examples are by Dean Hickerson
(see <a href="http://conwaylife.com/ref/DRH/stamps.html">http://conwaylife.com/ref/DRH/stamps.html</a>).
<p>Many stamp collections contain "fonts" made of single cells (which
cleanly die) to annotate the objects or to draw boxes around them.
For example, here is a stamp collection which shows all the ways that
two gliders can create a <a href="lex_l.htm#loaf">loaf</a> or an <a href="lex_e.htm#eater">eater</a>:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.O......O.O.....O....O.O.O...................O.$............................................O..$.O.....O...O...O.O...O......................OOO$...............................................$.O.....O...O..O...O..O.O.O.....................$...............................................$.O.....O...O..O.O.O..O.........................$........................................OO.....$.O.O.O..O.O...O...O..O.................O.O.....$.........................................O.....$...............................................$...............................................$.............................................O.$............................................O..$O.O.O....O....O.O.O..O.O.O..O.O.............OOO$................................O..............$O.......O.O.....O....O......O..................$................................O..............$O.O.O..O...O....O....O.O.O..O.O................$...............................................$O......O.O.O....O....O......O..O...........O...$..........................................OO...$O.O.O..O...O....O....O.O.O..O...O.........O.O..$"
>.O......O.O.....O....O.O.O...................O.
............................................O..
.O.....O...O...O.O...O......................OOO
...............................................
.O.....O...O..O...O..O.O.O.....................
...............................................
.O.....O...O..O.O.O..O.........................
........................................OO.....
.O.O.O..O.O...O...O..O.................O.O.....
.........................................O.....
...............................................
...............................................
.............................................O.
............................................O..
O.O.O....O....O.O.O..O.O.O..O.O.............OOO
................................O..............
O.......O.O.....O....O......O..................
................................O..............
O.O.O..O...O....O....O.O.O..O.O................
...............................................
O......O.O.O....O....O......O..O...........O...
..........................................OO...
O.O.O..O...O....O....O.O.O..O...O.........O.O..
</a></pre></td></tr></table></center>
<p>Alternatively, stamp collections can use <a href="lex_l.htm#lifehistory">LifeHistory</a> for their
annotations, but this requires a more sophisticated Life program to
handle. Numbers, or more rarely letters, are sometimes constructed
from stable components such as <a href="lex_b.htm#block">blocks</a> or <a href="#snake">snakes</a>, but their
readability is somewhat limited by placement constraints.
<p><a name=standardspaceship>:</a><b>standard spaceship</b> A <a href="lex_g.htm#glider">glider</a>, <a href="lex_l.htm#lwss">LWSS</a>, <a href="lex_m.htm#mwss">MWSS</a> or <a href="lex_h.htm#hwss">HWSS</a>. These have
all been known since 1970.
<p><a name=star>:</a><b>star</b> (p3) Found by Hartmut Holzwart, February 1993.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.....O.....$....OOO....$..OOO.OOO..$..O.....O..$.OO.....OO.$OO.......OO$.OO.....OO.$..O.....O..$..OOO.OOO..$....OOO....$.....O.....$"
>.....O.....
....OOO....
..OOO.OOO..
..O.....O..
.OO.....OO.
OO.......OO
.OO.....OO.
..O.....O..
..OOO.OOO..
....OOO....
.....O.....
</a></pre></td></tr></table></center>
<p><a name=stargate>:</a><b>star gate</b> A device by Dieter Leithner (October 1996) for transporting
a <a href="lex_l.htm#lwss">LWSS</a> faster than the <a href="#speedoflight">speed of light</a>. The key reaction is the
<a href="lex_f.htm#fastforwardforcefield">Fast Forward Force Field</a>.
<p><a name=stator>:</a><b>stator</b> The cells of an <a href="lex_o.htm#oscillator">oscillator</a> that are always on. Compare
<a href="lex_r.htm#rotor">rotor</a>. (The stator is sometimes taken to include also some of
those cells which are always off.) The stator is divided into the
<a href="lex_b.htm#bushing">bushing</a> and the <a href="lex_c.htm#casing">casing</a>.
<p>By analogy, the cells of an <a href="lex_e.htm#eater">eater</a> that remain on even when the
eater is eating are considered to constitute the stator of the eater.
This is not always well-defined, because an eater can have more than
one eating action.
<p><a name=statorless>:</a><b>statorless</b> A statorless <a href="lex_o.htm#oscillator">oscillator</a> is one in which no cell is
permanently on - that is, the <a href="#stator">stator</a> is empty, or in other words
the oscillator has the maximum possible volatility. See the
<a href="lex_v.htm#volatility">volatility</a> entry for examples of this type of oscillator at
different periods. Statorless oscillators can be constructed for any
sufficiently large period, using <a href="lex_u.htm#universalconstructor">universal constructor</a> technology.
<p><a name=statorlessp5>:</a><b>statorless p5</b> (p5) Found by Josh Ball, June 2016. The first and only
known <a href="#statorless">statorless</a> <a href="lex_p.htm#period">period</a> 5 <a href="lex_o.htm#oscillator">oscillator</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:O.............O$.OO.........OO.$O....OO.OO....O$OO.O.......O.OO$.O.O..O.O..O.O.$..O.O.....O.O..$..OOO.....OOO..$..OOO.....OOO..$..O.O.....O.O..$.O.O..O.O..O.O.$OO.O.......O.OO$O....OO.OO....O$.OO.........OO.$O.............O$"
>O.............O
.OO.........OO.
O....OO.OO....O
OO.O.......O.OO
.O.O..O.O..O.O.
..O.O.....O.O..
..OOO.....OOO..
..OOO.....OOO..
..O.O.....O.O..
.O.O..O.O..O.O.
OO.O.......O.OO
O....OO.OO....O
.OO.........OO.
O.............O
</a></pre></td></tr></table></center>
<p><a name=step>:</a><b>step</b> Another term for a <a href="lex_g.htm#generation">generation</a> or <a href="lex_t.htm#tick">tick</a>. This term is
particularly used in describing <a href="lex_c.htm#conduit">conduits</a>. For example, a 64-step
conduit is one through which the active object takes 64 generations
to pass.
<p><a name=stillater>:</a><b>stillater</b> (p3) Found by Robert Wainwright, September 1985. This is
one of only three essentially different p3 <a href="lex_o.htm#oscillator">oscillators</a> with only
three cells in the <a href="lex_r.htm#rotor">rotor</a>. The others are <a href="lex_1.htm#a-123">1-2-3</a> and <a href="lex_c.htm#cuphook">cuphook</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...O....$..O.O.OO$..O.OO.O$OO......$.O.O.OO.$.O.O..O.$..O..O..$...OO...$"
>...O....
..O.O.OO
..O.OO.O
OO......
.O.O.OO.
.O.O..O.
..O..O..
...OO...
</a></pre></td></tr></table></center>
<p><a name=stilllife>:</a><b>still life</b> Any <a href="#stable">stable</a> pattern, usually assumed to be finite and
nonempty. For the purposes of enumerating still lifes this
definition is, however, unsatisfactory because, for example, any pair
of blocks would count as a still life, and there would therefore be
an infinite number of 8-bit still lifes.
<p>For this reason a stricter definition is often used, counting a
stable pattern as a <a href="#strictstilllife">strict still life</a> only if its <a href="lex_i.htm#island">islands</a> cannot
be divided into two or more nonempty sets both of which are stable in
their own right. If such a subdivision can be made, the pattern can
be referred to as a <a href="lex_c.htm#constellation">constellation</a>. If its cells form a single
<a href="lex_c.htm#cluster">cluster</a> it is also, more specifically, either a <a href="lex_p.htm#pseudostilllife">pseudo still life</a>
or a <a href="lex_q.htm#quasistilllife">quasi still life</a>.
<p>In rare cases above a certain size threshold, a pattern may be
divisible into three or four stable nonempty subsets but not into
two. See the 32-bit <a href="lex_t.htm#triplepseudo">triple pseudo</a> (32 bits) and the 34-bit
<a href="lex_q.htm#quadpseudo">quad pseudo</a> for examples.
<p>All still lifes up to 18 bits have been shown to be
<a href="lex_g.htm#gliderconstructible">glider constructible</a>. It is an open question whether all still
lifes can be incrementally constructed using glider collisions. For
a subset of small still lifes that have been found to be especially
useful in <a href="#selfconstructing">self-constructing</a> circuitry, see also <a href="#spartan">Spartan</a>.
<p>The smallest still life is the <a href="lex_b.htm#block">block</a>. Arbitrarily large still
lifes are easy to construct, for example by extending a <a href="lex_c.htm#canoe">canoe</a> or
<a href="lex_b.htm#barge">barge</a>. The maximum density of a large still life is 1/2, which can
be achieved by an arbitrarily large patch of <a href="lex_z.htm#zebrastripes">zebra stripes</a> or
<a href="lex_c.htm#chickenwire">chicken wire</a>, among many other options. See <a href="lex_d.htm#density">density</a> for more
precise limits.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...O..O..O..O..O..O...$.OOOOOOOOOOOOOOOOOOOO.$O....................O$OOOOOOOOOOOOOOOOOOOOOO$......................$OOOOOOOOOOOOOOOOOOOOOO$O....................O$.OOOOOOOOOOOOOOOOOOOO.$......................$.OOOOOOOOOOOOOOOOOOOO.$O....................O$OOOOOOOOOOOOOOOOOOOOOO$......................$OOOOOOOOOOOOOOOOOOOOOO$O....................O$.OOOOOOOOOOOOOOOOOOOO.$......................$.OOOOOOOOOOOOOOOOOOOO.$O....................O$OOOOOOOOOOOOOOOOOOOOOO$......................$OOOOOOOOOOOOOOOOOOOOOO$O....................O$.OOOOOOOOOOOOOOOOOOOO.$...O..O..O..O..O..O...$"
>...O..O..O..O..O..O...
.OOOOOOOOOOOOOOOOOOOO.
O....................O
OOOOOOOOOOOOOOOOOOOOOO
......................
OOOOOOOOOOOOOOOOOOOOOO
O....................O
.OOOOOOOOOOOOOOOOOOOO.
......................
.OOOOOOOOOOOOOOOOOOOO.
O....................O
OOOOOOOOOOOOOOOOOOOOOO
......................
OOOOOOOOOOOOOOOOOOOOOO
O....................O
.OOOOOOOOOOOOOOOOOOOO.
......................
.OOOOOOOOOOOOOOOOOOOO.
O....................O
OOOOOOOOOOOOOOOOOOOOOO
......................
OOOOOOOOOOOOOOOOOOOOOO
O....................O
.OOOOOOOOOOOOOOOOOOOO.
...O..O..O..O..O..O...
</a></pre></td></tr></table></center>
<p><a name=stilllifetagalong>:</a><b>still life tagalong</b> A <a href="lex_t.htm#tagalong">tagalong</a> which takes the form of a
<a href="#stilllife">still life</a> in at least one <a href="lex_p.htm#phase">phase</a>. An example is shown below.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..OO...............$.OO.OO.............$..OOOO.............$...OO..............$...................$...OOOOO...........$..OOOOOOO..........$.OO.OOOOO..........$..OO...............$...................$........O.O.....OO.$......O....O...O..O$......OO.....O.O..O$.O..O..OOOO.O...OO.$O.......OO.........$O...O..............$OOOO...............$"
>..OO...............
.OO.OO.............
..OOOO.............
...OO..............
...................
...OOOOO...........
..OOOOOOO..........
.OO.OOOOO..........
..OO...............
...................
........O.O.....OO.
......O....O...O..O
......OO.....O.O..O
.O..O..OOOO.O...OO.
O.......OO.........
O...O..............
OOOO...............
</a></pre></td></tr></table></center>
<p><a name=stopandgo>:</a><b>stop and go</b> A pattern by Dean Hickerson in which a period 46
<a href="#shuttle">shuttle</a> converts a glider into a block on one oscillation, and then
converts the block back into a glider on the next oscillation. The
glider is reflected back onto its own path, but with a delay.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:........................................O.$.......................................O..$OO..............OO.........OO..........OOO$OO...............OO........OO.............$.............OOOOO........................$.............OOOO.........................$..........................................$.............OOOO.........................$.............OOOOO........................$OO...............OO.......................$OO..............OO........................$"
>........................................O.
.......................................O..
OO..............OO.........OO..........OOO
OO...............OO........OO.............
.............OOOOO........................
.............OOOO.........................
..........................................
.............OOOO.........................
.............OOOOO........................
OO...............OO.......................
OO..............OO........................
</a></pre></td></tr></table></center>
<p><a name=stopandrestart>:</a><b>stop and restart</b> A type of <a href="#signal">signal</a> <a href="lex_c.htm#circuit">circuit</a> where an input signal
is converted into a stationary object, which is then re-activated by
a secondary input signal. This can be used either as a memory device
storing one bit of information, or as a simple delay mechanism. In
the following January 2016 example by Martin Grant, a
<a href="lex_g.htm#ghostherschel">ghost Herschel</a> marks the output signal location, and a "ghost
<a href="lex_b.htm#beehive">beehive</a>" marks the location of the intermediate still life.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:........................................................O.$.......................................................O..$.......................................................OOO$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$............O.............................................$............OOO...........................................$...............O..........................................$..............OO..........................................$........O.................................................$.......O.O.......OO.......................................$.......O.O......O.O.......................................$.....OOO.OO.....OO........................................$....O.....................................................$.....OOO.OO...............................................$.......O.OO...............................................$..........................................................$..........................................................$..........................................................$OO........................................................$.O........................................................$.O.O......................................................$..OO......................................................$..........................................................$....................O.....................................$...................O.O....................................$...................O...................................O..$....................O................................OOO..$....................................OO...............O....$..O.................................OO...............O....$..O.O.....................................................$..OOO.....................................................$....O....................O................................$........................O.O...............................$........................OO................................$...................OO............OO.......................$...................OO............O........................$..................................O.......................$.................................OO.......................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..........................................................$..OO..........OO..........................................$...O..........O...........................................$OOO............OOO........................................$O................O........................................$"
>........................................................O.
.......................................................O..
.......................................................OOO
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
............O.............................................
............OOO...........................................
...............O..........................................
..............OO..........................................
........O.................................................
.......O.O.......OO.......................................
.......O.O......O.O.......................................
.....OOO.OO.....OO........................................
....O.....................................................
.....OOO.OO...............................................
.......O.OO...............................................
..........................................................
..........................................................
..........................................................
OO........................................................
.O........................................................
.O.O......................................................
..OO......................................................
..........................................................
....................O.....................................
...................O.O....................................
...................O...................................O..
....................O................................OOO..
....................................OO...............O....
..O.................................OO...............O....
..O.O.....................................................
..OOO.....................................................
....O....................O................................
........................O.O...............................
........................OO................................
...................OO............OO.......................
...................OO............O........................
..................................O.......................
.................................OO.......................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..........................................................
..OO..........OO..........................................
...O..........O...........................................
OOO............OOO........................................
O................O........................................
</a></pre></td></tr></table></center>
The <a href="lex_e.htm#eater1">eater1</a> in the lower left corner catches the restart glider if
no input signal has come in to create the beehive. This eater could
be removed if it is useful to have both a "0" and a "1" output for a
memory cell mechanism.
<p>The <a href="lex_c.htm#catchandthrow">catch and throw</a> <a href="lex_t.htm#technology">technology</a> in a <a href="lex_c.htm#caterpillar">Caterpillar</a> is a somewhat
similar idea. See also <a href="#stopandgo">stop and go</a> and <a href="lex_r.htm#reanimation">reanimation</a>.
<p><a name=stream>:</a><b>stream</b> A line of identical objects (usually <a href="#spaceship">spaceships</a>), each of
which is moving in a direction parallel to the line, generally on the
same <a href="lex_l.htm#lane">lane</a>. In many uses the stream is periodic. For example, the
<a href="lex_n.htm#newgun">new gun</a> produces a period 46 <a href="lex_g.htm#glider">glider</a> stream. The stream produced
by a <a href="lex_p.htm#pseudorandomglidergenerator">pseudo-random glider generator</a> can have a very high period.
Compare with <a href="lex_w.htm#wave">wave</a>. See also <a href="#singlechannel">single-channel</a> for a common use of
non-periodic <a href="lex_g.htm#glider">glider</a> streams.
<p><a name=stretcher>:</a><b>stretcher</b> Any pattern that grows by stretching a <a href="lex_w.htm#wick">wick</a> or <a href="lex_a.htm#agar">agar</a>.
See <a href="lex_w.htm#wickstretcher">wickstretcher</a> and <a href="#spacefiller">spacefiller</a>.
<p><a name=strictstilllife>:</a><b>strict still life</b> A <a href="#stilllife">still life</a> that is either a single connected
<a href="lex_p.htm#polyplet">polyplet</a>, or is arranged such that a <a href="#stable">stable</a> smaller pattern
cannot be formed by removing one or more of its <a href="lex_i.htm#island">islands</a>. For
example, <a href="lex_b.htm#beehivewithtail">beehive with tail</a> is a strict still life because it is
connected, and <a href="lex_t.htm#tableontable">table on table</a> is a strict still life because
neither of the <a href="lex_t.htm#table">tables</a> are stable by themselves. See also
<a href="lex_t.htm#triplepseudo">triple pseudo</a>, <a href="lex_q.htm#quadpseudo">quad pseudo</a>.
<p>Still lifes have been enumerated by Conway (4-7 bits), Robert
Wainwright (8-10 bits), Dave Buckingham (11-13 bits), Peter Raynham
(14 bits), Mark Niemiec (15-24 bits), and Simon Ekstr&ouml;m and Nathaniel
Johnston (25-32 bits). The resulting figures are shown below; see
also <a href="https://oeis.org/A019473">https://oeis.org/A019473</a>. The most recent search by Nathaniel
Johnston has also confirmed that the <a href="lex_t.htm#triplepseudo">triple pseudo</a> pattern found by
Gabriel Nivasch is the only such still life with 32 bits or less. It
is therefore included in the pseudo still life count and not in the
table below.
<pre>
  --------------
  Bits    Number
  --------------
   4           2
   5           1
   6           5
   7           4
   8           9
   9          10
  10          25
  11          46
  12         121
  13         240
  14         619
  15        1353
  16        3286
  17        7773
  18       19044
  19       45759
  20      112243
  21      273188
  22      672172
  23     1646147
  24     4051711
  25     9971377
  26    24619307
  27    60823008
  28   150613157
  29   373188952
  30   926068847
  31  2299616637
  32  5716948683
  --------------
</pre>
<p>As the number of bits increases, the strict still life count goes
up exponentially by approximately O(2.46<sup><i>n</i></sup>). By comparison, the rate
for pseudo still life}s is about O(2.56<sup><i>n</i></sup>) while for
<a href="lex_q.htm#quasistilllife">quasi still lifes</a> it's around O(3.04<sup><i>n</i></sup>).
<p><a name=strictvolatility>:</a><b>strict volatility</b> A term suggested by Noam Elkies in August 1998 for
the proportion of cells involved in a period <i>n</i> <a href="lex_o.htm#oscillator">oscillator</a> which
themselves oscillate with period <i>n</i>. For prime <i>n</i> this is the same as
the ordinary <a href="lex_v.htm#volatility">volatility</a>. Periods with known strictly-volatile
oscillators include 1, 2, 3, 5, 6, 8, 13, 15, 22, 30, 33, and 177.
Examples include <a href="lex_f.htm#figure8">figure-8</a>, <a href="lex_k.htm#koksgalaxy">Kok's galaxy</a>, <a href="#smiley">smiley</a>, and
<a href="lex_p.htm#pentadecathlon">pentadecathlon</a>. A composite example is the following p22, found by
Nicolay Beluchenko on 4 March 2009:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...........OO...$..........O.O...$..O.....O....O..$OO.OO..OO.O.O...$O.......O...O...$.O.O............$................$..OOO.......O...$...O.......OOO..$................$............O.O.$...O...O.......O$...O.O.OO..OO.OO$..O....O.....O..$...O.O..........$...OO...........$"
>...........OO...
..........O.O...
..O.....O....O..
OO.OO..OO.O.O...
O.......O...O...
.O.O............
................
..OOO.......O...
...O.......OOO..
................
............O.O.
...O...O.......O
...O.O.OO..OO.OO
..O....O.....O..
...O.O..........
...OO...........
</a></pre></td></tr></table></center>
<p><a name=superbeehive>:</a><b>super beehive</b> = <a href="lex_h.htm#honeycomb">honeycomb</a>
<p><a name=superfountain>:</a><b>superfountain</b> (p4) A p4 <a href="#sparker">sparker</a> which produces a 1-cell spark that
is separated from the rest of the oscillator by two clear rows of
cells. The first superfountain was found by Noam Elkies in February
1998. In January 2006 Nicolay Beluchenko found the much smaller one
shown below. See also <a href="lex_f.htm#fountain">fountain</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...........O...........$.......................$.......................$.....O..O.....O..O.....$...OO..O.OOOOO.O..OO...$.....O...........O.....$...O.OO.........OO.O...$.O.O...OOO...OOO...O.O.$OOO.O.............O.OOO$..........O.O..........$....OOO...O.O...OOO....$....O..O...O...O..O....$...OOOO..O.O.O..OOOO...$...OO..OOO.O.OOO..OO...$..O...O...O.O...O...O..$...O..O.O.O.O.O.O..O...$....O.O.OO...OO.O.O....$.....O...........O.....$"
>...........O...........
.......................
.......................
.....O..O.....O..O.....
...OO..O.OOOOO.O..OO...
.....O...........O.....
...O.OO.........OO.O...
.O.O...OOO...OOO...O.O.
OOO.O.............O.OOO
..........O.O..........
....OOO...O.O...OOO....
....O..O...O...O..O....
...OOOO..O.O.O..OOOO...
...OO..OOO.O.OOO..OO...
..O...O...O.O...O...O..
...O..O.O.O.O.O.O..O...
....O.O.OO...OO.O.O....
.....O...........O.....
</a></pre></td></tr></table></center>
<p><a name=superlineargrowth>:</a><b>superlinear growth</b> Growth faster than any rate proportional to T,
where T is the number of ticks that a pattern has been run. This
term usually applies to a pattern's population growth, rather than
diametric growth or bounding-box growth. For example, <a href="lex_b.htm#breeder">breeders</a>'
and <a href="#spacefiller">spacefillers</a>' population asymptotically grows faster than any
linear-growth pattern. It may also be used to describe the rate of
increase in the number of subpatterns present in a pattern, such as
when describing a <a href="lex_r.htm#replicator">replicator</a>'s rate of reproduction. Due to limits
enforced by the <a href="#speedoflight">speed of light</a>, no pattern's population can grow at
an asymptotic rate faster than <a href="lex_q.htm#quadraticgrowth">quadratic growth</a>. See
<a href="#switchenginepingpong">switch-engine ping-pong</a> for the lowest-population superlinear
growth pattern as of July 2018, along with a list of the
record-holders.
<p><a name=superstring>:</a><b>superstring</b> An infinite orthogonal row of cells stabilized on one
side so that it moves at the <a href="#speedoflight">speed of light</a>, often leaving debris
behind. The first examples were found in 1971 by Edward Fitzgerald
and Robert Wainwright. Superstrings were studied extensively by
Peter Rott during 1992-1994, and he found examples with many
different periods. (But no odd periods. In August 1998 Stephen
Silver proved that odd-period superstrings are impossible.)
<p>Sometimes a finite section of a superstring can be made to run
between two tracks ("waveguides"). This gives a <a href="lex_f.htm#fuse">fuse</a> which can be
made as wide as desired. The first example was found by Tony
Smithurst and uses <a href="lex_t.htm#tub">tubs</a>. (This is shown below. The superstring
itself is p4 with a repeating section of width 9 producing one
blinker per period and was one of those discovered in 1971. With the
track in place, however, the period is 8. This track can also be
used with a number of other superstrings.) Shortly after seeing this
example, in March 1997 Peter Rott found another superstring track
consisting of <a href="lex_b.htm#boat">boats</a>. At present these are the only two waveguides
known. Both are destroyed by the superstring as it moves along. It
would be interesting to find one that remains intact.
<p>See <a href="lex_t.htm#titanictoroidaltraveler">titanic toroidal traveler</a> for another example of a
superstring.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.OO..........................................................$O..O...O...O...O...O...O...O...O...O...O...O...O...O...O...O.$....O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O$O..O...O...O...O...O...O...O...O...O...O...O...O...O...O...O.$.OOO.........................................................$..OO.........................................................$..OO.........................................................$...O.........................................................$...O.........................................................$...O.........................................................$...O.........................................................$...O.........................................................$...O.........................................................$...O.........................................................$..OO.........................................................$..OO.........................................................$.OOO.........................................................$O..O...O...O...O...O...O...O...O...O...O...O...O...O...O...O.$....O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O$O..O...O...O...O...O...O...O...O...O...O...O...O...O...O...O.$.OO..........................................................$"
>.OO..........................................................
O..O...O...O...O...O...O...O...O...O...O...O...O...O...O...O.
....O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O
O..O...O...O...O...O...O...O...O...O...O...O...O...O...O...O.
.OOO.........................................................
..OO.........................................................
..OO.........................................................
...O.........................................................
...O.........................................................
...O.........................................................
...O.........................................................
...O.........................................................
...O.........................................................
...O.........................................................
..OO.........................................................
..OO.........................................................
.OOO.........................................................
O..O...O...O...O...O...O...O...O...O...O...O...O...O...O...O.
....O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O
O..O...O...O...O...O...O...O...O...O...O...O...O...O...O...O.
.OO..........................................................
</a></pre></td></tr></table></center>
<p><a name=support>:</a><b>support</b> Those parts of an object which are only present in order to
keep the rest of the object (such an <a href="lex_e.htm#engine">engine</a> or an edge <a href="#spark">spark</a>)
working correctly. These can be components of the object, or else
accompanying objects used to <a href="lex_p.htm#perturb">perturb</a> the object. In many cases
there is a wide variation of support possible for an engine. The
<a href="lex_a.htm#arm">arms</a> in many <a href="lex_p.htm#puffer">puffers</a> are an example of support.
<p><a name=surprise>:</a><b>surprise</b> (p3) Found by Dave Buckingham, November 1972.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...O....OO$...OOO..O.$.OO...O.O.$O..OO.O.OO$.O......O.$OO.O.OO..O$.O.O...OO.$.O..OOO...$OO....O...$"
>...O....OO
...OOO..O.
.OO...O.O.
O..OO.O.OO
.O......O.
OO.O.OO..O
.O.O...OO.
.O..OOO...
OO....O...
</a></pre></td></tr></table></center>
<p><a name=sw1t43>:</a><b>SW1T43</b> A <a href="lex_h.htm#herscheltoglider">Herschel-to-glider</a> converter that produces a
<a href="lex_t.htm#tandemglider">tandem glider</a> useful in the <a href="lex_t.htm#tee">tee</a> reaction. It is classified as a
"G3" converter because its two gliders are three <a href="lex_l.htm#lane">lanes</a> apart.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.......OO........$.......O.........$.....O.O.........$....O.O..........$OO...O...........$OO...............$...........OO....$...........O.O...$.............O...$.............O.OO$..........OO.O.OO$O........O..O....$O.O.......OO.....$OOO..............$..O.......OOOO...$...........O..O..$.........O...OO..$.........OO......$"
>.......OO........
.......O.........
.....O.O.........
....O.O..........
OO...O...........
OO...............
...........OO....
...........O.O...
.............O...
.............O.OO
..........OO.O.OO
O........O..O....
O.O.......OO.....
OOO..............
..O.......OOOO...
...........O..O..
.........O...OO..
.........OO......
</a></pre></td></tr></table></center>
Besides the southwest-travelling glider on lane 1, the converter also
emits the Herschel's standard <a href="lex_f.htm#firstnaturalglider">first natural glider</a>, <a href="#sw2">SW-2</a>. The
converter's full standard name is therefore "HSW1T43_SW-2T21". See
<a href="lex_n.htm#nw31">NW31</a> for an explanation of H-to-G naming conventions.
<p><a name=sw2>:</a><b>SW-2</b> The simplest type of <a href="lex_h.htm#htog">H-to-G</a> <a href="lex_c.htm#converter">converter</a>, where the converter's
effect is simply to suppress a Herschel cleanly after allowing its
<a href="lex_f.htm#firstnaturalglider">first natural glider</a> to escape. The name should be read as "SW
minus two", where -2 is a glider <a href="lex_l.htm#lane">lane</a> number. The complete
designation is SW-2T21. See <a href="lex_n.htm#nw31t120">NW31T120</a> for a discussion of the
standard naming conventions used for these converters.
<p>An unlimited number of converters have the SW-2T21 classification.
The variants most often used consist of just one or two small
<a href="#stilllife">still life</a> <a href="lex_c.htm#catalyst">catalysts</a>.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...................................OO.....$...................................O......$.................................O.O......$.............................OO..OO.......$.............................OO...........$.....OO...................................$.....OO...................................$.............................OO...........$.............................OO...........$..........................................$..........................................$..........................................$.........OO...............................$.........OO...............................$..........................................$O........................O................$O.O......................O.O..............$OOO......................OOO..............$..O........................O..............$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$..........................................$........................................O.$...........O...........................O.O$..........O.O...........................OO$..........O.O.............................$...........O............................OO$O........................O.............O.O$O.O......................O.O............O.$OOO......................OOO..............$..O........................O..............$"
>...................................OO.....
...................................O......
.................................O.O......
.............................OO..OO.......
.............................OO...........
.....OO...................................
.....OO...................................
.............................OO...........
.............................OO...........
..........................................
..........................................
..........................................
.........OO...............................
.........OO...............................
..........................................
O........................O................
O.O......................O.O..............
OOO......................OOO..............
..O........................O..............
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
..........................................
........................................O.
...........O...........................O.O
..........O.O...........................OO
..........O.O.............................
...........O............................OO
O........................O.............O.O
O.O......................O.O............O.
OOO......................OOO..............
..O........................O..............
</a></pre></td></tr></table></center>
<p><a name=sw2t21>:</a><b>SW-2T21</b> = <a href="#sw2">SW-2</a>
<p><a name=swan>:</a><b>swan</b> (<i>c</i>/4 diagonally, p4) A diagonal <a href="#spaceship">spaceship</a> producing some
useful sparks. Found by Tim Coe in February 1996.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.O..........OO..........$OOOOO......OO...........$O..OO........O.......OO.$..OO.O.....OO......OOO.O$...........OO...O.OO....$.....O.O......OO........$..........OOO.O....O....$.......OOO...O....O.....$........O.......O.......$........O......O........$........................$...........O............$"
>.O..........OO..........
OOOOO......OO...........
O..OO........O.......OO.
..OO.O.....OO......OOO.O
...........OO...O.OO....
.....O.O......OO........
..........OOO.O....O....
.......OOO...O....O.....
........O.......O.......
........O......O........
........................
...........O............
</a></pre></td></tr></table></center>
<p><a name=swimmer>:</a><b>swimmer</b> = <a href="#switchengine">switch engine</a>.
<p><a name=swimmerlane>:</a><b>swimmer lane</b> = <a href="#switchenginechannel">switch engine channel</a>.
<p><a name=switch>:</a><b>switch</b> A <a href="#signal">signal</a>-carrying <a href="lex_c.htm#circuit">circuit</a> that can send output signals to
two or more different locations, depending on the state of the
mechanism. These may be <a href="lex_t.htm#togglecircuit">toggle circuits</a>, where the state of the
switch changes after each use, or <a href="lex_p.htm#permanentswitch">permanent switches</a> that retain
the same state through many uses until a change is made with a
separate signal.
<p>More generally, any circuit may be referred to as a switch, if it
can alter its output based on stored information. For example, the
following simple mechanism based on an eater2 was discovered by
Emerson J. Perkins in 2007. It either reflects or absorbs an
incoming signal, depending on the presence or absence of a nearby
block. The block is removed if a reflection occurs.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:...O.....................O....................$....O...................O.O...................$..OOO...................O.O...................$......................OOO.OO................O.$..................O..O....................OOO.$................OOO...OOO.OO...OO........O....$...............O........O.OO...OO........OO...$...............OO.............................$OO............................................$.O............................................$.O.OO.........................................$..O..O....................................OO..$...OO.....................................O.O.$..................OO........................O.$..................OO........................OO$..................................OOO.........$..................................O...........$...................................O..........$..............................................$..........................O...OO..............$.........................O.O...O..............$.....................OO.O.O...O...............$.....................OO.O....O................$.........................OOOOO.O..............$.................OO.O.OO.O....OO...........OOO$.................O.OO.O..O.OO..............O..$..........OO............OO.O.OOO............O.$..........OO...................O..............$"
>...O.....................O....................
....O...................O.O...................
..OOO...................O.O...................
......................OOO.OO................O.
..................O..O....................OOO.
................OOO...OOO.OO...OO........O....
...............O........O.OO...OO........OO...
...............OO.............................
OO............................................
.O............................................
.O.OO.........................................
..O..O....................................OO..
...OO.....................................O.O.
..................OO........................O.
..................OO........................OO
..................................OOO.........
..................................O...........
...................................O..........
..............................................
..........................O...OO..............
.........................O.O...O..............
.....................OO.O.O...O...............
.....................OO.O....O................
.........................OOOOO.O..............
.................OO.O.OO.O....OO...........OOO
.................O.OO.O..O.OO..............O..
..........OO............OO.O.OOO............O.
..........OO...................O..............
</a></pre></td></tr></table></center>
<p>The switching signal here is a glider produced by a high-clearance
<a href="#syringe">syringe</a> variant found by Matthias Merzenich. The syringe is not
technically part of the switch mechanism; any standard <a href="lex_h.htm#herschel">Herschel</a>
source can deliver the signal to the block <a href="lex_f.htm#factory">factory</a> (the two
<a href="lex_e.htm#eater1">eater1s</a> on the right side of the pattern). Alternate <a href="lex_c.htm#converter">converter</a>
mechanisms could also be used to place the block.
<p>An earlier example of the same type of one-time switch mechanism,
also mediated by a block, can be found in the NW34T204 <a href="lex_h.htm#htog">H-to-G</a>. See
also <a href="lex_b.htm#bistableswitch">bistable switch</a> for a very robust and versatile toggle switch
with two input <a href="lex_l.htm#lane">lanes</a> and four possible outputs.
<p><a name=switchablegun>:</a><b>switchable gun</b> A <a href="lex_g.htm#gun">gun</a> that includes a mechanism to turn the output
stream off and on with simple signals, often gliders. A small
example is Dieter Leithner's switchable LWSS gun from July 8, 1995.
The ON signal enters from the northeast, and the OFF signal from the
northwest:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.................OO...........................................$.................O..O.........................................$..............................................................$.....................O........................................$..............................................................$.O.................OO.........................................$..O...............O...........................................$OOO...........................................................$..............................................................$...............OO...OO........................................$...............OO...OO........................................$................OOOOO........................O................$.................O.O........................O.................$............................................OOO...............$.................OOO..........................................$....................................O.O.......................$....................................O...O.....................$........................................O.......O.............$..........................OO........O....O....OOOO............$..........................OO............O....O.O.OO...........$.....................O..............O...O...O..O.OOO........OO$......................O.............O.O......O.O.OO.........OO$....................OOO.......................OOOO............$................O...............................O.............$...............OOO...................O........................$..............OOOOO..................O.O.....O................$.............OO...OO.................OO....OOO................$..........................................O...................$.............................O............OO..................$...........................O..O.........OOO...................$...............OOO..........OOO.........OO....................$...............OOO..........O..........O.O....................$.............................O................................$.............................OOO..............................$................OO............................................$................OO............................................$.....................O........................................$...................OOOO......OO..OO...........................$.............OO...O.O.OO.....OOOO.O..O.O......................$.............OO..O..O.OOO.....OO.O...O...O....................$..................O.O.OO....O............O.....OO.............$...................OOOO..............O....O....OO.............$.....................O...................O....................$.....................................O...O....................$.....................................O.O......................$"
>.................OO...........................................
.................O..O.........................................
..............................................................
.....................O........................................
..............................................................
.O.................OO.........................................
..O...............O...........................................
OOO...........................................................
..............................................................
...............OO...OO........................................
...............OO...OO........................................
................OOOOO........................O................
.................O.O........................O.................
............................................OOO...............
.................OOO..........................................
....................................O.O.......................
....................................O...O.....................
........................................O.......O.............
..........................OO........O....O....OOOO............
..........................OO............O....O.O.OO...........
.....................O..............O...O...O..O.OOO........OO
......................O.............O.O......O.O.OO.........OO
....................OOO.......................OOOO............
................O...............................O.............
...............OOO...................O........................
..............OOOOO..................O.O.....O................
.............OO...OO.................OO....OOO................
..........................................O...................
.............................O............OO..................
...........................O..O.........OOO...................
...............OOO..........OOO.........OO....................
...............OOO..........O..........O.O....................
.............................O................................
.............................OOO..............................
................OO............................................
................OO............................................
.....................O........................................
...................OOOO......OO..OO...........................
.............OO...O.O.OO.....OOOO.O..O.O......................
.............OO..O..O.OOO.....OO.O...O...O....................
..................O.O.OO....O............O.....OO.............
...................OOOO..............O....O....OO.............
.....................O...................O....................
.....................................O...O....................
.....................................O.O......................
</a></pre></td></tr></table></center>
<p><a name=switchengine>:</a><b>switch engine</b> The following pattern discovered by Charles Corderman
in 1971, which is a <a href="lex_g.htm#glidesymmetric">glide symmetric</a> unstable <a href="lex_p.htm#puffer">puffer</a> which moves
diagonally at a speed of <i>c</i>/12 (8 cells every 96 generations).
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:.O.O..$O.....$.O..O.$...OOO$"
>.O.O..
O.....
.O..O.
...OOO
</a></pre></td></tr></table></center>
<p>The <a href="lex_e.htm#exhaust">exhaust</a> is <a href="lex_d.htm#dirty">dirty</a> and unfortunately catches up and destroys
the switch engine before it runs 13 full periods. Corderman found
several ways to stabilize the switch engine to produce <a href="lex_p.htm#puffer">puffers</a>,
using either one or two switch engines in tandem. See
<a href="#stabilizedswitchengine">stabilized switch engine</a> and <a href="lex_a.htm#ark">ark</a>.
<p>No <a href="#spaceship">spaceships</a> were able to be made from switch engines until Dean
Hickerson found the first one in April 1991 (see <a href="lex_c.htm#cordership">Cordership</a>).
Switch engine <a href="lex_t.htm#technology">technology</a> is now well-advanced, producing many <i>c</i>/12
diagonal spaceships, puffers, and rakes of many periods.
<p>Small <a href="lex_p.htm#polyomino">polyominoes</a> exist whose <a href="lex_e.htm#evolution">evolution</a> results in a switch
engine. See <a href="lex_n.htm#nonominoswitchenginepredecessor">nonomino switch engine predecessor</a>.
<p>Several three-glider collisions produce <a href="lex_d.htm#dirty">dirty</a> reactions that
produce a stabilized switch engine along with other <a href="lex_a.htm#ash">ash</a>, making
<a href="lex_i.htm#infinitegrowth">infinite growth</a>. Until recently the only known syntheses for
<a href="lex_c.htm#clean">clean</a> unstabilized switch engines used four or more gliders. There
are several such recipes. In the reaction shown below no glider
arrives from the direction that the switch engine will travel to,
making it easier to repeat the reaction:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:OOO................$..O................$.O.................$...................$.......OO..........$......OO...........$........O..........$...................$...................$...................$...................$...................$...................$...................$..OO...............$.O.O...............$...O...............$...................$................OOO$................O..$.................O.$"
>OOO................
..O................
.O.................
...................
.......OO..........
......OO...........
........O..........
...................
...................
...................
...................
...................
...................
...................
..OO...............
.O.O...............
...O...............
...................
................OOO
................O..
.................O.
</a></pre></td></tr></table></center>
Running the above for 20 ticks completes a <a href="lex_k.htm#kickback">kickback</a> reaction with
the top two gliders, resulting in the three-glider switch engine
recipe discovered by Luka Okanishi on 12 March 2017.
<p><a name=switchenginechannel>:</a><b>switch engine channel</b> Two lines of <a href="lex_b.htm#boat">boats</a> (or other suitable
objects, such as <a href="lex_t.htm#tubwithtail">tub with tails</a>) arranged so that a <a href="#switchengine">switch engine</a>
can travel between them, in the following manner:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..............OO................$.............O.O................$..............O.................$................................$................................$................................$................................$................................$.......OOO............OO........$........O..O.........O.O........$............O.........O.........$.........O.O....................$................................$................................$................................$................................$..............................OO$.............................O.O$..............................O.$................................$................................$.O..............................$O.O.............................$OO..............................$................................$................................$................................$................................$................................$.........O......................$........O.O.....................$........OO......................$"
>..............OO................
.............O.O................
..............O.................
................................
................................
................................
................................
................................
.......OOO............OO........
........O..O.........O.O........
............O.........O.........
.........O.O....................
................................
................................
................................
................................
..............................OO
.............................O.O
..............................O.
................................
................................
.O..............................
O.O.............................
OO..............................
................................
................................
................................
................................
................................
.........O......................
........O.O.....................
........OO......................
</a></pre></td></tr></table></center>
David Bell used this in June 2005 to construct a "bobsled"
oscillator, in which a switch engine <a href="lex_f.htm#factory">factory</a> sends switch engines
down a channel, at the other end of which they are deleted.
<p><a name=switchenginechute>:</a><b>switch engine chute</b> = <a href="#switchenginechannel">switch engine channel</a>
<p><a name=switchenginepingpong>:</a><b>switch-engine ping-pong</b> A very large (210515x183739)
<a href="lex_q.htm#quadraticgrowth">quadratic growth</a> pattern found by Michael Simkin in October 2014.
Currently this is the smallest starting population (23 cells) known
to result in a quadratic population growth rate. Previous
record-holders include <a href="lex_j.htm#jaws">Jaws</a>, <a href="lex_m.htm#mosquito1">mosquito1</a>, <a href="lex_m.htm#mosquito2">mosquito2</a>, <a href="lex_m.htm#mosquito3">mosquito3</a>,
<a href="lex_m.htm#mosquito4">mosquito4</a>, <a href="lex_m.htm#mosquito5">mosquito5</a>, <a href="lex_t.htm#teeth">teeth</a>, <a href="lex_c.htm#catacryst">catacryst</a>, <a href="lex_m.htm#metacatacryst">metacatacryst</a>,
<a href="lex_g.htm#gottsdots">Gotts dots</a>, <a href="lex_w.htm#wedge">wedge</a>, <a href="lex_1.htm#a-26cellquadraticgrowth">26-cell quadratic growth</a>,
<a href="lex_1.htm#a-25cellquadraticgrowth">25-cell quadratic growth</a>, and <a href="lex_1.htm#a-24cellquadraticgrowth">24-cell quadratic growth</a>.
<p><a name=symmetric>:</a><b>symmetric</b> Any object which can be rotated and/or flipped over an axis
and still maintain the same shape. Many common small objects such as
the <a href="lex_b.htm#block">block</a>, <a href="lex_b.htm#beehive">beehive</a>, <a href="lex_p.htm#pond">pond</a>, <a href="lex_l.htm#loaf">loaf</a>, <a href="lex_c.htm#clock">clock</a>, and <a href="lex_b.htm#blinker">blinker</a> are
symmetric. Some larger symmetric objects are <a href="lex_k.htm#koksgalaxy">Kok's galaxy</a>,
<a href="lex_a.htm#achimsp16">Achim's p16</a>, <a href="lex_c.htm#cross">cross</a>, <a href="lex_e.htm#eureka">Eureka</a>, and the <a href="lex_p.htm#pulsar">pulsar</a>.
<p>Large symmetric objects can easily be created by placing multiple
copies of any finite object together in a symmetrical way. Unless
the individual objects interact significantly, this is considered
trivial and is not considered further here (e.g., two <a href="lex_l.htm#lwss">LWSSs</a>
travelling together a hundred cells apart).
<p>There are two kinds of symmetry. Odd symmetry occurs when an
object's line of reflection passes through the center of a line of
cells. Objects with odd symmetry have an odd number of columns or
rows, and can have a <a href="lex_g.htm#gutter">gutter</a>. Even symmetry occurs when the line of
reflection follows the boundary between two lines of cells. Objects
with even symmetry have an even number of columns or rows.
<p>Because the Life universe and its rules are symmetric, all
symmetric objects must remain symmetric throughout their <a href="lex_e.htm#evolution">evolution</a>.
Most non-symmetric objects keep their non-symmetry as they evolve,
but some can become symmetric, especially if they result in a single
object. Here is a slightly more complicated example where two
gliders interact to form a <a href="lex_b.htm#blockade">blockade</a>:
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:..O.........$O.O.........$.OO........O$.........OO.$..........OO$"
>..O.........
O.O.........
.OO........O
.........OO.
..........OO
</a></pre></td></tr></table></center>
<p>Many useful objects are symmetric along an orthogonal axis. This
commonly occurs by placing two copies of an object side by side to
change the behaviour of the objects due to the inhibition or killing
of new cells at their <a href="lex_g.htm#gutter">gutter</a> interface. Examples of this are
<a href="lex_t.htm#twinbeesshuttle">twin bees shuttle</a>, <a href="lex_c.htm#centinal">centinal</a>, and the object shown in <a href="lex_p.htm#puffer">puffer</a>.
Other useful symmetric objects are created by perturbing a symmetric
object using nearby <a href="lex_o.htm#oscillator">oscillators</a> or <a href="#spaceship">spaceships</a> in a symmetric
manner. Examples of this are <a href="#schickengine">Schick engine</a>, <a href="lex_b.htm#blinkership">blinker ship</a>, and
<a href="lex_h.htm#hivenudger">hivenudger</a>.
<p>Many <a href="#spaceship">spaceships</a> found by <a href="#searchprogram">search programs</a> are symmetric because
the search space for such objects is much smaller than for
non-symmetrical spaceships. Examples include <a href="lex_d.htm#dart">dart</a>, <a href="lex_1.htm#a-60p5h2v0">60P5H2V0</a>, and
<a href="lex_1.htm#a-119p4h1v0">119P4H1V0</a>.
<p><a name=synchronized>:</a><b>synchronized</b> Indicates that precise relative timing is required for
two or more input <a href="#signal">signals</a> entering a <a href="lex_c.htm#circuit">circuit</a>, or two or more sets
of <a href="lex_g.htm#glider">gliders</a> participating in a <a href="lex_g.htm#glidersynthesis">glider synthesis</a>. Compare
<a href="lex_a.htm#asynchronous">asynchronous</a>. See also <a href="#salvo">salvo</a> and <a href="#slowgliderconstruction">slow glider construction</a>.
<p><a name=synchronous>:</a><b>synchronous</b> = <a href="#synchronized">synchronized</a>
<p><a name=synthesis>:</a><b>synthesis</b> = <a href="lex_g.htm#glidersynthesis">glider synthesis</a>
<p><a name=syringe>:</a><b>syringe</b> A small stable <a href="lex_c.htm#converter">converter</a> found by Tanner Jacobi in March
2015, accepting a glider as input and producing an output <a href="lex_h.htm#herschel">Herschel</a>
As of June 2018 it is the smallest known converter of this type, so
it is very often used to handle input gliders in complex <a href="#signal">signal</a>
<a href="lex_c.htm#circuit">circuitry</a>, as described in <a href="lex_h.htm#herschelcircuit">Herschel circuit</a>. A second glider can
safely follow the first any time after 78 ticks, but <a href="lex_o.htm#overclocking">overclocking</a>
also allows the syringe to work at a <a href="lex_r.htm#repeattime">repeat time</a> of 74 or 75 ticks.
If followed by a <a href="lex_d.htm#dependentconduit">dependent conduit</a> a simple <a href="lex_e.htm#eater2">eater2</a> can be used
instead of the large <a href="lex_w.htm#weld">welded</a> <a href="lex_c.htm#catalyst">catalyst</a> shown here. A
<a href="lex_g.htm#ghostherschel">ghost Herschel</a> marks the output location.
<center><table cellspacing=0 cellpadding=0><tr><td><pre><a href="lexpatt:....O.............................$.....O............................$...OOO............................$..................O...............$................OOO...............$...............O..................$...............OO.................$OO................................$.O................................$.O.OO.............................$..O..O.......................O....$...OO........................O....$..................OO.........OOO..$..................OO...........O..$..................................$..................................$..................................$...........................O...OO.$..........................O.O...O.$.........................O.O...O..$.....................OO.O.O...O...$.....................OO.O..OOOO.O.$.........................O.O...O.O$.....................OO.OO..O..O.O$......................O.O..OO...O.$..........OO..........O.O.........$..........OO...........O..........$"
>....O.............................
.....O............................
...OOO............................
..................O...............
................OOO...............
...............O..................
...............OO.................
OO................................
.O................................
.O.OO.............................
..O..O.......................O....
...OO........................O....
..................OO.........OOO..
..................OO...........O..
..................................
..................................
..................................
...........................O...OO.
..........................O.O...O.
.........................O.O...O..
.....................OO.O.O...O...
.....................OO.O..OOOO.O.
.........................O.O...O.O
.....................OO.OO..O..O.O
......................O.O..OO...O.
..........OO..........O.O.........
..........OO...........O..........
</a></pre></td></tr></table></center>
<p>A different version of the large catalyst, with better <a href="lex_c.htm#clearance">clearance</a>
for some situations, can be seen in the <a href="#switch">switch</a> entry.
<hr>
<center>
<b>
<a href="lex_1.htm">1-9</a> |
<a href="lex_a.htm">A</a> |
<a href="lex_b.htm">B</a> |
<a href="lex_c.htm">C</a> |
<a href="lex_d.htm">D</a> |
<a href="lex_e.htm">E</a> |
<a href="lex_f.htm">F</a> |
<a href="lex_g.htm">G</a> |
<a href="lex_h.htm">H</a> |
<a href="lex_i.htm">I</a> |
<a href="lex_j.htm">J</a> |
<a href="lex_k.htm">K</a> |
<a href="lex_l.htm">L</a> |
<a href="lex_m.htm">M</a> |
<a href="lex_n.htm">N</a> |
<a href="lex_o.htm">O</a> |
<a href="lex_p.htm">P</a> |
<a href="lex_q.htm">Q</a> |
<a href="lex_r.htm">R</a> |
<a href="lex_s.htm">S</a> |
<a href="lex_t.htm">T</a> |
<a href="lex_u.htm">U</a> |
<a href="lex_v.htm">V</a> |
<a href="lex_w.htm">W</a> |
<a href="lex_x.htm">X</a> |
<a href="lex_y.htm">Y</a> |
<A href="lex_z.htm">Z</A></b>

</center>
<hr>
</body>