MATCH_ACCEPT_TAC : thm_tactic
STRUCTURE
Tactic
SYNOPSIS
Solves a goal which is an instance of the supplied theorem.
DESCRIPTION
When given a theorem A' |- t and a goal A ?- t' where t can be matched to t' by instantiating variables which are either free or universally quantified at the outer level, including appropriate type instantiation, MATCH_ACCEPT_TAC completely solves the goal. 
    A ?- t'
   =========  MATCH_ACCEPT_TAC (A' |- t)
Unless A' is a subset of A, this is an invalid tactic.
FAILURE
Fails unless the theorem has a conclusion which is instantiable to match that of the goal.
EXAMPLE
The following example shows variable and type instantiation at work. We can use the polymorphic list theorem HD: 
   HD = |- !h t. HD(CONS h t) = h
to solve the goal: 
   ?- HD [1;2] = 1
simply by: 
   MATCH_ACCEPT_TAC HD
COMMENTS
prim_irule is similar, with differences in the details
SEEALSO
ACCEPT_TAC, prim_irule
HOL  Kananaskis-14