Tactic.FILTER_GEN

STRUCTURE

SYNOPSIS

Strips off a universal quantifier, but fails for a given quantified variable.

DESCRIPTION

When applied to a term s and a goal A ?- !x. t, the tactic FILTER_GEN_TAC fails if the quantified variable x is the same as s, but otherwise advances the goal in the same way as GEN_TAC, i.e. returns the goal 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
   ==============  FILTER_GEN_TAC "s"
    A ?- t[x'/x]

FAILURE

Fails if the goal’s conclusion is not universally quantified or the quantified variable is equal to the given term.

SEEALSO

GEN, GEN_TAC, GENL, GEN_ALL, SPEC, SPECL, SPEC_ALL, SPEC_TAC, STRIP_TAC