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GEN_TAC : tactic

SYNOPSIS

Strips the outermost universal quantifier from the conclusion of a goal.

DESCRIPTION

When applied to a goal A ?- !x. t, the tactic GEN_TAC reduces it to A ?- t[x'/x] where x' is a variant of x chosen to avoid clashing with any variables free in the goal's assumption list. Normally x' is just x.

     A ?- !x. t
   ==============  GEN_TAC
    A ?- t[x'/x]

FAILURE CONDITIONS

Fails unless the goal's conclusion is universally quantified.

USES

The tactic REPEAT GEN_TAC strips away any universal quantifiers, and is commonly used before tactics relying on the underlying term structure.