File: basic_congs.doc

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\DOC basic_congs

\TYPE {basic_congs : unit -> thm list}

\SYNOPSIS
Lists the congruence rules used by the simplifier.

\DESCRIBE
The HOL Light simplifier (as invoked by {SIMP_TAC} etc.) uses congruence rules
to determine how it uses context when descending through a term. These are
essentially theorems showing how to decompose one equality to a series of other
inequalities in context. A call to {basic_congs()} returns those congruences
that are built into the system.

\FAILURE
Never fails.

\EXAMPLE
Here is the effect in HOL Light's initial state:
{
  # basic_congs();;
  val it : thm list =
    [|- (!x. x IN s ==> f x = g x) ==> sum s (\i. f i) = sum s g;
     |- (!i. a <= i /\ i <= b ==> f i = g i)
        ==> sum (a..b) (\i. f i) = sum (a..b) g;
     |- (!x. p x ==> f x = g x) ==> sum {{y | p y}} (\i. f i) = sum {{y | p y}} g;
     |- (!x. x IN s ==> f x = g x) ==> nsum s (\i. f i) = nsum s g;
     |- (!i. a <= i /\ i <= b ==> f i = g i)
        ==> nsum (a..b) (\i. f i) = nsum (a..b) g;
     |- (!x. p x ==> f x = g x) ==> nsum {{y | p y}} (\i. f i) = nsum {{y | p y}} g;
     |- (g <=> g')
        ==> (g' ==> t = t')
        ==> (~g' ==> e = e')
        ==> (if g then t else e) = (if g' then t' else e');
     |- (p <=> p') ==> (p' ==> (q <=> q')) ==> (p ==> q <=> p' ==> q')]
}

\SEEALSO
extend_basic_congs, set_basic_congs, SIMP_CONV, SIMP_RULE, SIMP_TAC.

\ENDDOC