<Chapter Label="ChangesGAP49toGAP410"> 
<Heading>Changes between &GAP; 4.9 and &GAP; 4.10</Heading>

This chapter contains an overview of the most important changes
introduced in &GAP; 4.10.0 release (the first public release of &GAP; 4.10).
Later it will also contain information about subsequent update 
releases for &GAP; 4.10.
<P/>

These changes are also listed on the Wiki page
<URL>https://github.com/gap-system/GAP/wiki/gap-4.10-release-notes</URL>.

<Section Label="GAP4.10.0">
<Heading>&GAP; 4.10.0 (November 2018)</Heading>

<Subsection> 
<Heading>New features and major changes</Heading>

<List>

<!-- 
 -->
<Mark>Reduce impact of immediate methods</Mark><Item>

&GAP; allows declaring so-called <Q>immediate methods</Q>. The idea is that these
are very simple and fast methods which are immediately called if
information about an object becomes known, in order to perform some quick
deduction. For example, if the order of a group is set, there might be
immediate methods which update the filters <C>IsFinite</C> and <C>IsTrivial</C> of the
group suitably.
<P/>

While this can be very elegant and useful in interactive &GAP; sessions, the
overhead for running these immediate methods and applying their results can
become a major factor in the runtime of complex computations that create
thousands or millions of objects.
<P/>

To address this, various steps were taken:
<List>
<Item>some immediate methods were turned into regular methods;
</Item>
<Item>a special handlers for <C>SetSize</C> was created that deduces properties
which previously were taken care of by immediate methods;
</Item>
<Item>some immediate methods were replaced by implications
(set via <C>InstallTrueMethod</C>), a mechanism that essentially
adds zero overhead, unlike immediate methods;
</Item>
<Item>various group constructors were modified to precompute and preset
properties of freshly created group objects, to avoid triggering immediate
methods for these.
</Item>
</List>

As a result of these and other changes, consider the following example;
with &GAP; 4.9, it takes about 130 seconds on one test system, while with
&GAP; 4.10 it runs in about 22 seconds, i.e., more than six times faster.
<Log><![CDATA[
G:=PcGroupCode( 741231213963541373679312045151639276850536621925972119311,11664);;
IsomorphismGroups(G,PcGroupCode(CodePcGroup(G),Size(G)))<>fail;
]]></Log>

Relevant pull requests and issues:
<URL><LinkText>&Hash;2386</LinkText><Link>https://github.com/gap-system/gap/pull/2386</Link></URL>,
<URL><LinkText>&Hash;2387</LinkText><Link>https://github.com/gap-system/gap/pull/2387</Link></URL>,
<URL><LinkText>&Hash;2522</LinkText><Link>https://github.com/gap-system/gap/pull/2522</Link></URL>.
</Item>

<!-- 
 -->
<Mark>Change definition of <C>IsPGroup</C> to <E>not</E> require finiteness</Mark><Item>

This is a small change in terms of amount of code changed, but we list it here
as it has a potential (albeit rather unlikely) impact on the code written by &GAP;
users:
In the past, the &GAP; manual entry for <C>IsPGroup</C> defined <M>p</M>-groups as being
finite groups, which differs from the most commonly used definition for
<M>p</M>-groups. Note however that there was not actual implication installed from
<C>IsPGroup</C> to <C>IsFinite</C>, so it always was possible to actually created
infinite groups in the filter <C>IsPGroup</C>.

In &GAP; 4.10, we adjusted (in <URL><LinkText>&Hash;1545</LinkText><Link>https://github.com/gap-system/gap/pull/1545</Link></URL>)
the documentation for <C>IsPGroup</C> to the commonly accepted definition for
<M>p</M>-groups. In addition, code in the &GAP; library and in packages using
<C>IsPGroup</C> was audited and (in a very few cases) adjusted to explicitly check
<C>IsFinite</C> (see e.g. <URL><LinkText>&Hash;2866</LinkText><Link>https://github.com/gap-system/gap/pull/2866</Link></URL>).
</Item>

<!-- 
 -->
<Mark>Experimental support for using the <Package>Julia</Package> garbage collector</Mark><Item>

It is now possible to use the garbage collector of the <URL Text="Julia language">https://julialang.org</URL>
instead of &GAP;'s traditional <Package>GASMAN</Package> garbage collector. This is partly
motivated by a desire to allow tight integration with &GAP; and <Package>Julia</Package> in the
future. Warning: right now, this is <E>slower</E>, and also requires a patched
version of <Package>Julia</Package>.
<P/>

Relevant pull requests:
<URL><LinkText>&Hash;2092</LinkText><Link>https://github.com/gap-system/gap/pull/2092</Link></URL>,
<URL><LinkText>&Hash;2408</LinkText><Link>https://github.com/gap-system/gap/pull/2408</Link></URL>,
<URL><LinkText>&Hash;2461</LinkText><Link>https://github.com/gap-system/gap/pull/2461</Link></URL>,
<URL><LinkText>&Hash;2485</LinkText><Link>https://github.com/gap-system/gap/pull/2485</Link></URL>,
<URL><LinkText>&Hash;2495</LinkText><Link>https://github.com/gap-system/gap/pull/2495</Link></URL>,
<URL><LinkText>&Hash;2672</LinkText><Link>https://github.com/gap-system/gap/pull/2672</Link></URL>,
<URL><LinkText>&Hash;2688</LinkText><Link>https://github.com/gap-system/gap/pull/2688</Link></URL>,
<URL><LinkText>&Hash;2793</LinkText><Link>https://github.com/gap-system/gap/pull/2793</Link></URL>,
<URL><LinkText>&Hash;2904</LinkText><Link>https://github.com/gap-system/gap/pull/2904</Link></URL>,
<URL><LinkText>&Hash;2905</LinkText><Link>https://github.com/gap-system/gap/pull/2905</Link></URL>,
<URL><LinkText>&Hash;2931</LinkText><Link>https://github.com/gap-system/gap/pull/2931</Link></URL>.
</Item>

<!-- 
 -->
<Mark><Package>libGAP</Package> (work in progress)</Mark><Item>

We now provide a experimental way to allow 3rd party code to link &GAP; as a
library; this is based on the <Package>libGAP</Package> code by
<URL Text="SageMath">https://www.sagemath.org</URL>, but different: while we aim to provide the same
functionality, we do not rename any symbols, and we do not provide the same API.
We hope that a future version of <Package>SageMath</Package> can drop its custom modifications for
&GAP; and use this interface instead. Work is underway to achieve this goal.

If you are interested in this kind of interface, please get in touch with us to help us improve it.
See also <URL Text="this email">https://mail.gap-system.org/pipermail/gap/2018-August/001123.html</URL>.
<P/>

To get an idea how <Package>libGAP</Package> works, you can configure &GAP; as normal, and then execute
<C>make testlibgap</C> which will build a small program that uses some of the existing API and links
&GAP;.

Relevant pull requests:
<List>
<Item><URL><LinkText>&Hash;1690</LinkText><Link>https://github.com/gap-system/gap/pull/1690</Link></URL>
      Add a callback to <C>FuncJUMP_TO_CATCH</C>

</Item>
<Item><URL><LinkText>&Hash;2528</LinkText><Link>https://github.com/gap-system/gap/pull/2528</Link></URL>
      Add <C>IsLIBGAP</C> constant

</Item>
<Item><URL><LinkText>&Hash;2702</LinkText><Link>https://github.com/gap-system/gap/pull/2702</Link></URL>
      Add &GAP; kernel API

</Item>
<Item><URL><LinkText>&Hash;2723</LinkText><Link>https://github.com/gap-system/gap/pull/2723</Link></URL>
      Introduce command line options <C>--norepl</C> and <C>--nointeract</C>
</Item>
</List>

</Item>


</List>


</Subsection> 

<Subsection> 
<Heading>Improved and extended functionality</Heading>

<List>
<Item><URL><LinkText>&Hash;2041</LinkText><Link>https://github.com/gap-system/gap/pull/2041</Link></URL>
      Teach <C>FrattiniSubgroup</C> methods to check for solvability 

</Item>
<Item><URL><LinkText>&Hash;2053</LinkText><Link>https://github.com/gap-system/gap/pull/2053</Link></URL>
      Faster computation of modular inverses of integers

</Item>
<Item><URL><LinkText>&Hash;2057</LinkText><Link>https://github.com/gap-system/gap/pull/2057</Link></URL>
      Various changes, including:
  <List>
  <Item>Improve computation of automorphism groups for fp groups (we still recommend to instead first convert the group to a computationally nice representation, such as a perm or pc group)</Item>
  <Item>Add <Ref Attr="MinimalFaithfulPermutationDegree" BookName="ref"/> attribute for finite groups</Item>
  <Item>Improve performance of <C>GQuotients(F,G)</C> when <C>F</C> is an fp group</Item>
  <Item>Some other performance and documentation tweaks</Item>
  </List>


</Item>
<Item><URL><LinkText>&Hash;2061</LinkText><Link>https://github.com/gap-system/gap/pull/2061</Link></URL>,
      <URL><LinkText>&Hash;2086</LinkText><Link>https://github.com/gap-system/gap/pull/2086</Link></URL>,
      <URL><LinkText>&Hash;2159</LinkText><Link>https://github.com/gap-system/gap/pull/2159</Link></URL>,
      <URL><LinkText>&Hash;2306</LinkText><Link>https://github.com/gap-system/gap/pull/2306</Link></URL>
      Speed up <C>GcdInt</C>, <C>LcmInt</C>, <C>PValuation</C>, <C>RootInt</C>, <C>SmallestRootInt</C>, <C>IsPrimePowerInt</C>

</Item>
<Item><URL><LinkText>&Hash;2063</LinkText><Link>https://github.com/gap-system/gap/pull/2063</Link></URL>
      Teach &GAP; that BPSW pseudo primes less than <M>2^{64}</M> are all known to be prime (the previous limit was <M>10^{13}</M>)

</Item>
<Item><URL><LinkText>&Hash;2091</LinkText><Link>https://github.com/gap-system/gap/pull/2091</Link></URL>
      Refactor <C>DeclareAttribute</C> and <C>NewAttribute</C> (arguments are now verified stricter)

</Item>
<Item><URL><LinkText>&Hash;2115</LinkText><Link>https://github.com/gap-system/gap/pull/2115</Link></URL>,
      <URL><LinkText>&Hash;2204</LinkText><Link>https://github.com/gap-system/gap/pull/2204</Link></URL>,
      <URL><LinkText>&Hash;2272</LinkText><Link>https://github.com/gap-system/gap/pull/2272</Link></URL>
      Allow (optionally) passing a random source to many more <C>Random</C> methods than before, and also to <C>RandomList</C>

</Item>
<Item><URL><LinkText>&Hash;2136</LinkText><Link>https://github.com/gap-system/gap/pull/2136</Link></URL>
      Add <C>shortname</C> entry to record returned by <C>IsomorphismTypeInfoFiniteSimpleGroup</C>
</Item>
<Item><URL><LinkText>&Hash;2181</LinkText><Link>https://github.com/gap-system/gap/pull/2181</Link></URL>
      Implement <C>Union(X,Y)</C>, where <C>X</C> and <C>Y</C> are in
      <C>PositiveIntegers</C>, <C>NonnegativeIntegers</C>, <C>Integers</C>,
      <C>GaussianIntegers</C>, <C>Rationals</C>, <C>GaussianRationals</C>, <C>Cyclotomics</C>,
      at least where a suitable output object exists (we already provided
      <C>Intersection(X,Y)</C> for a long time)
</Item>
<Item><URL><LinkText>&Hash;2185</LinkText><Link>https://github.com/gap-system/gap/pull/2185</Link></URL>
      Implement <C>IsCentral(M,x)</C>, where <C>M</C> is a magma, monoid, group, ring, algebra, etc.
      and <C>x</C> an element of <C>M</C> (the documentation already claimed that these exist for a long time) 
</Item>
<Item><URL><LinkText>&Hash;2199</LinkText><Link>https://github.com/gap-system/gap/pull/2199</Link></URL>
      Optimize true/false conditions when coding if-statements
</Item>
<Item><URL><LinkText>&Hash;2200</LinkText><Link>https://github.com/gap-system/gap/pull/2200</Link></URL>
      Add <Ref Func="StringFormatted" BookName="ref"/>, <Ref Func="PrintFormatted" BookName="ref"/>,
      <Ref Func="PrintToFormatted" BookName="ref"/>
</Item>
<Item><URL><LinkText>&Hash;2222</LinkText><Link>https://github.com/gap-system/gap/pull/2222</Link></URL>
      Turn hidden implications into actual implications
</Item>
<Item><URL><LinkText>&Hash;2223</LinkText><Link>https://github.com/gap-system/gap/pull/2223</Link></URL>
      Add operation <Ref Oper="PositionsBound" BookName="ref"/> which returns the set of all bound positions in a given list
</Item>
<Item><URL><LinkText>&Hash;2224</LinkText><Link>https://github.com/gap-system/gap/pull/2224</Link></URL>,
      <URL><LinkText>&Hash;2243</LinkText><Link>https://github.com/gap-system/gap/pull/2243</Link></URL>,
      <URL><LinkText>&Hash;2340</LinkText><Link>https://github.com/gap-system/gap/pull/2340</Link></URL>
      Improve <C>ShowImpliedFilters</C> output
</Item>
<Item><URL><LinkText>&Hash;2225</LinkText><Link>https://github.com/gap-system/gap/pull/2225</Link></URL>
      Improve <C>LocationFunc</C> for kernel function
</Item>
<Item><URL><LinkText>&Hash;2232</LinkText><Link>https://github.com/gap-system/gap/pull/2232</Link></URL>
      Make <C>ValueGlobal</C> faster
</Item>
<Item><URL><LinkText>&Hash;2242</LinkText><Link>https://github.com/gap-system/gap/pull/2242</Link></URL>
      Add global function <Ref Func="CycleFromList" BookName="ref"/>
</Item>
<Item><URL><LinkText>&Hash;2244</LinkText><Link>https://github.com/gap-system/gap/pull/2244</Link></URL>
      Make <C>rank</C> argument to <C>InstallImmediateMethod</C> optional, similar to <C>InstallMethod</C>
</Item>
<Item><URL><LinkText>&Hash;2274</LinkText><Link>https://github.com/gap-system/gap/pull/2274</Link></URL>
      Ensure uniform printing of machine floats <C>nan</C>, <C>inf</C>, <C>-inf</C> across different operating systems
</Item>
<Item><URL><LinkText>&Hash;2287</LinkText><Link>https://github.com/gap-system/gap/pull/2287</Link></URL>
      Turn <C>IsInfiniteAbelianizationGroup</C> into a property and add some implications involving it
</Item>
<Item><URL><LinkText>&Hash;2293</LinkText><Link>https://github.com/gap-system/gap/pull/2293</Link></URL>,
      <URL><LinkText>&Hash;2602</LinkText><Link>https://github.com/gap-system/gap/pull/2602</Link></URL>,
      <URL><LinkText>&Hash;2718</LinkText><Link>https://github.com/gap-system/gap/pull/2718</Link></URL>
      Improved and documented various kernel and memory debugging facilities (requires recompiling &GAP;
      with <C>--enable-debug</C>, <C>--enable-valgrind</C> resp. <C>--enable-memory-checking</C>)
      <!-- documented in doc/dev manual -->
</Item>
<Item><URL><LinkText>&Hash;2308</LinkText><Link>https://github.com/gap-system/gap/pull/2308</Link></URL>
      Method selection code was rewritten from &GAP; to C
</Item>
<Item><URL><LinkText>&Hash;2326</LinkText><Link>https://github.com/gap-system/gap/pull/2326</Link></URL>
      Change <C>SimpleGroup</C> to perform better input validation and improve or correct error message for type 2E
</Item>
<Item><URL><LinkText>&Hash;2375</LinkText><Link>https://github.com/gap-system/gap/pull/2375</Link></URL>
      Make <C>last2</C> and <C>last3</C> available in break loops
</Item>
<Item><URL><LinkText>&Hash;2383</LinkText><Link>https://github.com/gap-system/gap/pull/2383</Link></URL>
      Speed improvements for automorphism groups
</Item>
<Item><URL><LinkText>&Hash;2393</LinkText><Link>https://github.com/gap-system/gap/pull/2393</Link></URL>
      Track location of <C>InstallMethod</C> and <C>InstallImmediateMethod</C>
</Item>
<Item><URL><LinkText>&Hash;2422</LinkText><Link>https://github.com/gap-system/gap/pull/2422</Link></URL>
      Improve tracking of <C>InstallMethod</C> and <C>DeclareOperation</C>
</Item>
<Item><URL><LinkText>&Hash;2426</LinkText><Link>https://github.com/gap-system/gap/pull/2426</Link></URL>
      Speed up <C>InverseMatMod</C> with integer modulus
</Item>
<Item><URL><LinkText>&Hash;2427</LinkText><Link>https://github.com/gap-system/gap/pull/2427</Link></URL>
      Fix and complete support for custom functions (i.e., objects which can be called like a function using <C>obj(arg)</C> syntax)
</Item>
<Item><URL><LinkText>&Hash;2456</LinkText><Link>https://github.com/gap-system/gap/pull/2456</Link></URL>
      Add <C>PrintString</C> and <C>ViewString</C> methods for character tables
</Item>
<Item><URL><LinkText>&Hash;2474</LinkText><Link>https://github.com/gap-system/gap/pull/2474</Link></URL>
      Change <C>IsConstantRationalFunction</C> and <C>IsUnivariateRationalFunction</C> to return 
      <K>false</K> if input isn't a rational function (instead of an error)
</Item>
<Item><URL><LinkText>&Hash;2474</LinkText><Link>https://github.com/gap-system/gap/pull/2474</Link></URL>
      Add methods for multiplying rational functions over arbitrary rings by rationals
</Item>
<Item><URL><LinkText>&Hash;2496</LinkText><Link>https://github.com/gap-system/gap/pull/2496</Link></URL>
      Finite groups whose order is known and not divisible by 4 are immediately marked as solvable
</Item>
<Item><URL><LinkText>&Hash;2509</LinkText><Link>https://github.com/gap-system/gap/pull/2509</Link></URL>
      Rewrite support for <File>.gz</File> compressed files to use <Package>zlib</Package>, now works on Windows
</Item>
<Item><URL><LinkText>&Hash;2519</LinkText><Link>https://github.com/gap-system/gap/pull/2519</Link></URL>,
      <URL><LinkText>&Hash;2524</LinkText><Link>https://github.com/gap-system/gap/pull/2524</Link></URL>,
      <URL><LinkText>&Hash;2531</LinkText><Link>https://github.com/gap-system/gap/pull/2531</Link></URL>
      <C>Test</C> now rejects empty inputs and warns if the input contains no test
</Item>
<Item><URL><LinkText>&Hash;2574</LinkText><Link>https://github.com/gap-system/gap/pull/2574</Link></URL>
      When reporting syntax errors, &GAP; now <Q>underlines</Q> the complete last token, not just the position where it stopped parsing
</Item>
<Item><URL><LinkText>&Hash;2577</LinkText><Link>https://github.com/gap-system/gap/pull/2577</Link></URL>,
      <URL><LinkText>&Hash;2613</LinkText><Link>https://github.com/gap-system/gap/pull/2613</Link></URL>
      Add quadratic and bilinear add forms for <C>Omega(e,d,q)</C>
</Item>
<Item><URL><LinkText>&Hash;2598</LinkText><Link>https://github.com/gap-system/gap/pull/2598</Link></URL>
      Add <C>BannerFunction</C> to <F>PackageInfo.g</F>
</Item>
<Item><URL><LinkText>&Hash;2606</LinkText><Link>https://github.com/gap-system/gap/pull/2606</Link></URL>
      Improve <C>PageSource</C> to work on functions that were read from a file given by a relative path
</Item>
<Item><URL><LinkText>&Hash;2616</LinkText><Link>https://github.com/gap-system/gap/pull/2616</Link></URL>
      Speed up computation of quotients of associative words by using existing (but previously unused) kernel functions for that
</Item>
<Item><URL><LinkText>&Hash;2640</LinkText><Link>https://github.com/gap-system/gap/pull/2640</Link></URL>
      Work on <C>MatrixObj</C> and <C>VectorObj</C>
</Item>
<Item><URL><LinkText>&Hash;2654</LinkText><Link>https://github.com/gap-system/gap/pull/2654</Link></URL>
      Make <C>Sortex</C> stable
</Item>
<Item><URL><LinkText>&Hash;2666</LinkText><Link>https://github.com/gap-system/gap/pull/2666</Link></URL>,
      <URL><LinkText>&Hash;2686</LinkText><Link>https://github.com/gap-system/gap/pull/2686</Link></URL>
      Add <C>IsBiCoset</C> attribute for right cosets, which is true if the right coset is also a left coset
</Item>
<Item><URL><LinkText>&Hash;2684</LinkText><Link>https://github.com/gap-system/gap/pull/2684</Link></URL>
      Add <C>NormalSubgroups</C> methods for symmetric and alternating permutation groups
</Item>
<Item><URL><LinkText>&Hash;2726</LinkText><Link>https://github.com/gap-system/gap/pull/2726</Link></URL>
      Validate <F>PackageInfo.g</F> when loading packages
</Item>
<Item><URL><LinkText>&Hash;2733</LinkText><Link>https://github.com/gap-system/gap/pull/2733</Link></URL>
      Minor performance improvements, code cleanup and very local fixes
</Item>
<Item><URL><LinkText>&Hash;2750</LinkText><Link>https://github.com/gap-system/gap/pull/2750</Link></URL>
      Reject some invalid uses of <C>~</C>
</Item>
<Item><URL><LinkText>&Hash;2812</LinkText><Link>https://github.com/gap-system/gap/pull/2812</Link></URL>
      Reduce memory usage and improve performance the MTC (modified Todd-Coxeter) code
      that was rewritten in &GAP; 4.9, but which was much slower than the old (but buggy)
      code it replaced; the difference is now small, but the old code still is faster in some case.
</Item>
<Item><URL><LinkText>&Hash;2855</LinkText><Link>https://github.com/gap-system/gap/pull/2855</Link></URL>,
      <URL><LinkText>&Hash;2877</LinkText><Link>https://github.com/gap-system/gap/pull/2877</Link></URL>
      Add <Ref Func="IsPackageLoaded" BookName="ref"/>
</Item>
<Item><URL><LinkText>&Hash;2878</LinkText><Link>https://github.com/gap-system/gap/pull/2878</Link></URL>
      Speed up conjugacy tests for permutation by using random permutation of points when selecting base in centraliser
</Item>
<Item><URL><LinkText>&Hash;2899</LinkText><Link>https://github.com/gap-system/gap/pull/2899</Link></URL>
      <C>TestDirectory</C> reports number of failures and failed files
</Item>
</List>

</Subsection> 

<Subsection> 
<Heading>Changed documentation</Heading>

<List>
<Item><URL><LinkText>&Hash;2192</LinkText><Link>https://github.com/gap-system/gap/pull/2192</Link></URL>
      Add an example for <Ref Oper="PRump" BookName="ref"/>
</Item>
<Item><URL><LinkText>&Hash;2219</LinkText><Link>https://github.com/gap-system/gap/pull/2219</Link></URL>
      Add examples to the relations chapter (see <Ref Chap="Relations" BookName="ref"/>).
</Item>
<Item><URL><LinkText>&Hash;2360</LinkText><Link>https://github.com/gap-system/gap/pull/2360</Link></URL>
      Document <Ref Func="IdealDecompositionsOfPolynomial" BookName="ref"/> (also accessible via its
      synonym <C>DecomPoly</C>) and <Ref Func="NormalizerViaRadical" BookName="ref"/>
</Item>
<Item><URL><LinkText>&Hash;2366</LinkText><Link>https://github.com/gap-system/gap/pull/2366</Link></URL>
      Do not recommend avoiding <C>X</C> which is a synonym for <Ref Oper="Indeterminate" BookName="ref"/>
</Item>
<Item><URL><LinkText>&Hash;2432</LinkText><Link>https://github.com/gap-system/gap/pull/2432</Link></URL>
      Correct a claim about the index of <C>Omega(e,p,q)</C> in <C>SO(e,p,q)</C>
      (see <Ref Func="SO" BookName="ref"/>)
</Item>
<Item><URL><LinkText>&Hash;2549</LinkText><Link>https://github.com/gap-system/gap/pull/2549</Link></URL>
      Update documentation of the <C>-T</C> command line option (see <Ref Sect="Command Line Options" BookName="ref"/>)
</Item>
<Item><URL><LinkText>&Hash;2551</LinkText><Link>https://github.com/gap-system/gap/pull/2551</Link></URL>
      Add new command line option <C>--alwaystrace</C> which ensures error backtraces are printed even if break loops are disabled
      (see <Ref Sect="Command Line Options" BookName="ref"/>)
</Item>
<Item><URL><LinkText>&Hash;2681</LinkText><Link>https://github.com/gap-system/gap/pull/2681</Link></URL>
      Documented <Ref Attr="ClassPositionsOfSolvableRadical" BookName="ref"/> and
      <Ref Func="CharacterTableOfNormalSubgroup" BookName="ref"/>
</Item>
<Item><URL><LinkText>&Hash;2834</LinkText><Link>https://github.com/gap-system/gap/pull/2834</Link></URL>
      Improve manual section about <C>Info</C> classes (see <Ref Sect="Info Functions" BookName="ref"/>)
</Item>
</List>

</Subsection> 

<Subsection> 
<Heading>Fixed bugs that could lead to crashes</Heading>

<List>
<Item><URL><LinkText>&Hash;2154</LinkText><Link>https://github.com/gap-system/gap/pull/2154</Link></URL>,
      <URL><LinkText>&Hash;2242</LinkText><Link>https://github.com/gap-system/gap/pull/2242</Link></URL>,
      <URL><LinkText>&Hash;2294</LinkText><Link>https://github.com/gap-system/gap/pull/2294</Link></URL>,
      <URL><LinkText>&Hash;2344</LinkText><Link>https://github.com/gap-system/gap/pull/2344</Link></URL>,
      <URL><LinkText>&Hash;2353</LinkText><Link>https://github.com/gap-system/gap/pull/2353</Link></URL>,
      <URL><LinkText>&Hash;2736</LinkText><Link>https://github.com/gap-system/gap/pull/2736</Link></URL>
      Fix several potential (albeit rare) crashes related to garbage collection
</Item>
<Item><URL><LinkText>&Hash;2196</LinkText><Link>https://github.com/gap-system/gap/pull/2196</Link></URL>
      Fix crash in <C>HasKeyBag</C> on SPARC Solaris 11
</Item>
<Item><URL><LinkText>&Hash;2305</LinkText><Link>https://github.com/gap-system/gap/pull/2305</Link></URL>
      Fix crash in <C>PartialPerm([1,2,8],[3,4,1,2]);</C>
</Item>
<Item><URL><LinkText>&Hash;2477</LinkText><Link>https://github.com/gap-system/gap/pull/2477</Link></URL>
      Fix crash if <C>~</C> is used to modify list
</Item>
<Item><URL><LinkText>&Hash;2499</LinkText><Link>https://github.com/gap-system/gap/pull/2499</Link></URL>
      Fix crash in the kernel functions <C>{8,16,32}Bits_ExponentSums3</C>
</Item>
<Item><URL><LinkText>&Hash;2601</LinkText><Link>https://github.com/gap-system/gap/pull/2601</Link></URL>
      Fix crash in <C>MakeImmutable(rec(x:=~));</C>
</Item>
<Item><URL><LinkText>&Hash;2665</LinkText><Link>https://github.com/gap-system/gap/pull/2665</Link></URL>
      Fix crash when an empty filename is passed
</Item>
<Item><URL><LinkText>&Hash;2711</LinkText><Link>https://github.com/gap-system/gap/pull/2711</Link></URL>
      Fix crash when tracing buggy attribute/property methods that fail to return a value
</Item>
<Item><URL><LinkText>&Hash;2766</LinkText><Link>https://github.com/gap-system/gap/pull/2766</Link></URL>
      Fix obscure crashes by using <C>a!{l}</C> syntax inside a function (this syntax never was fully implemented and was unusable, and now has been removed)
</Item>
</List>

</Subsection> 

<Subsection> 
<Heading>Fixed bugs that could lead to incorrect results</Heading>

<List>
<Item><URL><LinkText>&Hash;2085</LinkText><Link>https://github.com/gap-system/gap/pull/2085</Link></URL>
      Fix bugs in <C>JenningsLieAlgebra</C> and <C>PCentralLieAlgebra</C> that could e.g. lead to incorrect <C>LieLowerCentralSeries</C> results
</Item>
<Item><URL><LinkText>&Hash;2113</LinkText><Link>https://github.com/gap-system/gap/pull/2113</Link></URL>
      Fix <C>IsMonomial</C> for reducible characters and some related improvements
</Item>
<Item><URL><LinkText>&Hash;2183</LinkText><Link>https://github.com/gap-system/gap/pull/2183</Link></URL>
      Fix bug in <C>ValueMolienSeries</C> that could lead to <C>ValueMolienSeries(m,0)</C> not being 1
</Item>
<Item><URL><LinkText>&Hash;2198</LinkText><Link>https://github.com/gap-system/gap/pull/2198</Link></URL>
      Make multiplication of larger integers by tiny floats commutative (e.g. now <M>10.^{-300} * 10^{400}</M>
      and <M>10^{400} * 10.^-300</M> both give infinity, while before <M>10^{400} * 10.^{-300}</M> gave <M>1.e+100</M>);
      also ensure various strange inputs, like <C>rec()^1;</C>, produce an error (instead of setting
      <C>a^1 = a</C> and <C>1*a = a</C> for almost any kind of object)
</Item>
<Item><URL><LinkText>&Hash;2273</LinkText><Link>https://github.com/gap-system/gap/pull/2273</Link></URL>
      Fix <C>TypeOfOperation</C> for setters of and-filters
</Item>
<Item><URL><LinkText>&Hash;2275</LinkText><Link>https://github.com/gap-system/gap/pull/2275</Link></URL>,
      <URL><LinkText>&Hash;2280</LinkText><Link>https://github.com/gap-system/gap/pull/2280</Link></URL>
      Fix <C>IsFinitelyGeneratedGroup</C> and <C>IsFinitelyGeneratedMonoid</C> to not (incorrectly) assume that a given infinite generating set implies that there is no finite generating set
</Item>
<Item><URL><LinkText>&Hash;2311</LinkText><Link>https://github.com/gap-system/gap/pull/2311</Link></URL>
      Do not set <C>IsFinitelyGeneratedGroup</C> for finitely generated magmas which are not groups
</Item>
<Item><URL><LinkText>&Hash;2452</LinkText><Link>https://github.com/gap-system/gap/pull/2452</Link></URL>
      Fix bug that allowed creating empty magmas in the filters <C>IsTrivial</C> and <C>IsMagmaWithInverses</C>
</Item>
<Item><URL><LinkText>&Hash;2689</LinkText><Link>https://github.com/gap-system/gap/pull/2689</Link></URL>
      Fix <C>LogFFE</C> to not return negative results on 32 bit systems
</Item>
<Item><URL><LinkText>&Hash;2766</LinkText><Link>https://github.com/gap-system/gap/pull/2766</Link></URL>
      Fix a bug that allowed creating corrupt permutations
</Item>
</List>

</Subsection> 

<Subsection> 
<Heading>Fixed bugs that could lead to break loops</Heading>

<List>
<Item><URL><LinkText>&Hash;2040</LinkText><Link>https://github.com/gap-system/gap/pull/2040</Link></URL>
      Raise error if eager float literal conversion fails (fixes <URL><LinkText>&Hash;1105</LinkText><Link>https://github.com/gap-system/gap/pull/1105</Link></URL>)
</Item>
<Item><URL><LinkText>&Hash;2582</LinkText><Link>https://github.com/gap-system/gap/pull/2582</Link></URL>
      Fix <C>ExtendedVectors</C> for trivial vector spaces
</Item>
<Item><URL><LinkText>&Hash;2617</LinkText><Link>https://github.com/gap-system/gap/pull/2617</Link></URL>
      Fix <C>HighestWeightModule</C> for Lie algebras in certain cases
</Item>
<Item><URL><LinkText>&Hash;2829</LinkText><Link>https://github.com/gap-system/gap/pull/2829</Link></URL>
      Fix <C>ShallowCopy</C> for <C>IteratorOfCartesianProduct</C>
</Item>
</List>

</Subsection> 

<Subsection> 
<Heading>Other fixed bugs</Heading>

<List>
<Item><URL><LinkText>&Hash;2220</LinkText><Link>https://github.com/gap-system/gap/pull/2220</Link></URL>
      Do not set <C>IsSubsetLocallyFiniteGroup</C> filter for finite fields
</Item>
<Item><URL><LinkText>&Hash;2268</LinkText><Link>https://github.com/gap-system/gap/pull/2268</Link></URL>
      Handle spaces in filenames of gzipped filenames
</Item>
<Item><URL><LinkText>&Hash;2269</LinkText><Link>https://github.com/gap-system/gap/pull/2269</Link></URL>,
      <URL><LinkText>&Hash;2660</LinkText><Link>https://github.com/gap-system/gap/pull/2660</Link></URL>
      Fix some issues with the interface between &GAP; and <Package>XGAP</Package> (or other similar frontends for &GAP;)
</Item>
<Item><URL><LinkText>&Hash;2315</LinkText><Link>https://github.com/gap-system/gap/pull/2315</Link></URL>
      Prevent creation of groups of floats, just like we prevent creation of groups of cyclotomics
</Item>
<Item><URL><LinkText>&Hash;2350</LinkText><Link>https://github.com/gap-system/gap/pull/2350</Link></URL>
      Fix prompt after line continuation
</Item>
<Item><URL><LinkText>&Hash;2365</LinkText><Link>https://github.com/gap-system/gap/pull/2365</Link></URL>
      Fix tracing of mutable variants of <C>One</C>/<C>Zero</C>/<C>Inv</C>/<C>AInv</C>
</Item>
<Item><URL><LinkText>&Hash;2398</LinkText><Link>https://github.com/gap-system/gap/pull/2398</Link></URL>
      Fix <C>PositionStream</C> to report correct position
</Item>
<Item><URL><LinkText>&Hash;2467</LinkText><Link>https://github.com/gap-system/gap/pull/2467</Link></URL>
      Fix support for identifiers of length 1023 and more
</Item>
<Item><URL><LinkText>&Hash;2470</LinkText><Link>https://github.com/gap-system/gap/pull/2470</Link></URL>
      Do not display garbage after certain syntax error messages
</Item>
<Item><URL><LinkText>&Hash;2533</LinkText><Link>https://github.com/gap-system/gap/pull/2533</Link></URL>
      Fix composing a map with an identity map to not produce a range that is too big
</Item>
<Item><URL><LinkText>&Hash;2638</LinkText><Link>https://github.com/gap-system/gap/pull/2638</Link></URL>
      Fix result of <C>Random</C> on 64 bit big endian system to match those on little endian, and on 32 bit big endian
</Item>
<Item><URL><LinkText>&Hash;2672</LinkText><Link>https://github.com/gap-system/gap/pull/2672</Link></URL>
      Fix <C>MakeImmutable</C> for weak pointer objects, which previously failed to make subobjects immutable
</Item>
<Item><URL><LinkText>&Hash;2674</LinkText><Link>https://github.com/gap-system/gap/pull/2674</Link></URL>
      Fix <C>SaveWorkspace</C> to return <K>false</K> in case of an error, and <K>true</K> only if successful
</Item>
<Item><URL><LinkText>&Hash;2681</LinkText><Link>https://github.com/gap-system/gap/pull/2681</Link></URL>
      Fix <C>Display</C> for the character table of a trivial group
</Item>
<Item><URL><LinkText>&Hash;2716</LinkText><Link>https://github.com/gap-system/gap/pull/2716</Link></URL>
      When seeding a Mersenne twister from a string, the last few characters would not be used if the string length was not a multiple of 4. Fixing this may lead to different series of random numbers being generated.
</Item>
<Item><URL><LinkText>&Hash;2720</LinkText><Link>https://github.com/gap-system/gap/pull/2720</Link></URL>
      Reject workspaces made in a &GAP; with readline support in a &GAP; without, and vice versa, instead of crashing
</Item>
<Item><URL><LinkText>&Hash;2657</LinkText><Link>https://github.com/gap-system/gap/pull/2657</Link></URL>
      The subobjects of the mutable values of the attributes <C>ComputedClassFusions</C>, <C>ComputedIndicators</C>, <C>ComputedPowerMaps</C>, <C>ComputedPrimeBlockss</C> are now immutable.  This makes sure that the values are not accidentally changed.  This change may have side-effects in users' code, for example the object returned by <C>0 * ComputedPowerMaps( CharacterTable( "A5" ) )[2]</C> had been a mutable list before the change, and is an immutable list from now on.
</Item>
</List>

</Subsection> 

<Subsection> 
<Heading>Removed or obsolete functionality</Heading>

<List>
<Item>Remove multiple undocumented internal functions. Nobody should have been using them, but if you were, you may extract it from a previous &GAP; release that still contained it. (<URL><LinkText>&Hash;2670</LinkText><Link>https://github.com/gap-system/gap/pull/2670</Link></URL>,
      <URL><LinkText>&Hash;2781</LinkText><Link>https://github.com/gap-system/gap/pull/2781</Link></URL>
      and more)
</Item>
<Item><URL><LinkText>&Hash;2335</LinkText><Link>https://github.com/gap-system/gap/pull/2335</Link></URL>
      Remove several functions and variables that were deprecated for a long time: <C>DiagonalizeIntMatNormDriven</C>, <C>DeclarePackageDocumentation</C>, <C>KERNEL_VERSION</C>, <C>GAP_ROOT_PATHS</C>, <C>LOADED_PACKAGES</C>, <C>PACKAGES_VERSIONS</C>, <C>IsTuple</C>, <C>StateRandom</C>, <C>RestoreStateRandom</C>, <C>StatusRandom</C>, <C>FactorCosetOperation</C>, <C>ShrinkCoeffs</C>, <C>ExcludeFromAutoload</C>, <C>CharacterTableDisplayPrintLegendDefault</C>, <C>ConnectGroupAndCharacterTable</C>, <C>IsSemilatticeAsSemigroup</C>, <C>CreateCompletionFiles</C>, <C>PositionFirstComponent</C>, <C>ViewLength</C>
</Item>
<Item><URL><LinkText>&Hash;2502</LinkText><Link>https://github.com/gap-system/gap/pull/2502</Link></URL>
      Various kernel functions now validate their inputs more carefully (making it harder to produce bad effects by accidentally passing bad data to them)
</Item>
<Item><URL><LinkText>&Hash;2700</LinkText><Link>https://github.com/gap-system/gap/pull/2700</Link></URL>
      Forbid constructors with 0 arguments (they were never meaningful)
</Item>
</List>

</Subsection> 

<Subsection> 
<Heading>Packages</Heading>

&GAP; 4.10.0 distribution includes 140 packages.
<P/>

Added to the distribution:
<List>
<Item>
The <Package>francy</Package> package by Manuel Martins, which provides an interface
to draw graphics using objects. This interface allows creation of directed and
undirected graphs, trees, line charts, bar charts and scatter charts. These
graphical objects are drawn inside a canvas that includes a space for menus and
to display informative messages. Within the canvas it is possible to interact
with the graphical objects by clicking, selecting, dragging and zooming.
</Item>
<Item>
The <Package>JupyterVis</Package> package by Nathan Carter, which is intended for use
in Jupyter Notebooks running GAP kernels and adds visualization tools for use
in such notebooks, such as charts and graphs.
</Item>
</List>

No longer redistributed with &GAP;:

<List>
<Item>The <Package>linboxing</Package> package has been unusable (it does not
compile) for several years now, and is unmaintained. It was therefore dropped
from the &GAP; package distribution. If anybody is willing to take over and
fix the package, the latest sources are available at
<URL>https://github.com/gap-packages/linboxing</URL>.
</Item>
<Item>The <Package>recogbase</Package> package has been merged into the
<C>recog</C> package, and therefore is no longer distributed with &GAP;.
</Item>
</List>

</Subsection> 

</Section>

</Chapter>