\DOC ONCE_REWRITE_RULE
\TYPE {ONCE_REWRITE_RULE : (thm list -> thm -> thm)}
\SYNOPSIS
Rewrites a theorem, including built-in tautologies in the list of
rewrites.
\KEYWORDS
rule.
\DESCRIBE
{ONCE_REWRITE_RULE} searches for matching subterms and applies
rewrites once at each subterm, in the manner specified for
{ONCE_DEPTH_CONV}. The rewrites which are used are obtained from the
given list of theorems and the set of tautologies stored in
{basic_rewrites}. See {GEN_REWRITE_RULE} for the general method of
using theorems to rewrite an object theorem.
\FAILURE
{ONCE_REWRITE_RULE} does not fail; it does not diverge.
\USES
{ONCE_REWRITE_RULE} can be used to rewrite a theorem when recursive
rewriting is not desired.
\SEEALSO
Rewrite.ASM_REWRITE_RULE, Rewrite.GEN_REWRITE_RULE,
Rewrite.ONCE_ASM_REWRITE_RULE, Rewrite.PURE_ONCE_REWRITE_RULE,
Rewrite.PURE_REWRITE_RULE, Rewrite.REWRITE_RULE.
\ENDDOC