1\DOC
2
3\TYPE {COMB2_CONV : conv * conv -> conv}
4
5\SYNOPSIS
6Applies two conversions to an application's subterms.
7
8\KEYWORDS
9rewriting.
10
11\DESCRIBE
12
13A call to {COMB2_CONV(c1,c2) t}, when {t} is an application term of
14the form {f x}, causes conversion {c1} to be applied to term {f}, and
15conversion {c2} to be applied to term {x}. If the results of these
16calls are theorems of the form {|- f = f���} and {|- x = x���}, then the
17result of the call to {COMB2_CONV} is the theorem {|- f x = f��� x���}.
18
19If one of the two sub-calls raises the {UNCHANGED} exception, then the
20result of that call is taken to be the reflexive theorem ({|- x = x}
21if {c2} raises the exception, for example). If both conversions raise
22the {UNCHANGED} exception, then so too does {COMB2_CONV(c1,c2) t}.
23
24\FAILURE
25Fails if the term is not a combination term, or if either conversion fails when applied to the respective sub-terms.
26
27\EXAMPLE
28{
29> COMB2_CONV (ALL_CONV, numLib.REDUCE_CONV) ``f (10 * 3)``;
30<<HOL message: inventing new type variable names: 'a>>
31val it = |- f (10 * 3) = f 30 : thm
32}
33
34\SEEALSO
35Conv.ABS_CONV, Conv.COMB_CONV, Conv.FORK_CONV, Conv.RAND_CONV, Conv.RATOR_CONV.
36
37\ENDDOC
38