PSTRIP_GOAL_THEN : (thm_tactic -> tactic)

- STRUCTURE
- LIBRARY
- pair
- SYNOPSIS
- Splits a goal by eliminating one outermost connective, applying the given theorem-tactic to the antecedents of implications.
- DESCRIPTION
- Given a theorem-tactic ttac and a goal (A,t), PSTRIP_GOAL_THEN removes one outermost occurrence of one of the connectives !, ==>, ~ or /\ from the conclusion of the goal t. If t is a universally quantified term, then STRIP_GOAL_THEN strips off the quantifier. Note that PSTRIP_GOAL_THEN will strip off paired universal quantifications.where p' is a primed variant that contains no variables that appear free in the assumptions A. If t is a conjunction, then PSTRIP_GOAL_THEN simply splits the conjunction into two subgoals:
A ?- !p. u ============== PSTRIP_GOAL_THEN ttac A ?- u[p'/p]

If t is an implication "u ==> v" and if:A ?- v /\ w ================= PSTRIP_GOAL_THEN ttac A ?- v A ?- w

then:A ?- v =============== ttac (u |- u) A' ?- v'

Finally, a negation ~t is treated as the implication t ==> F.A ?- u ==> v ==================== PSTRIP_GOAL_THEN ttac A' ?- v'

- FAILURE
- PSTRIP_GOAL_THEN ttac (A,t) fails if t is not a paired universally quantified term, an implication, a negation or a conjunction. Failure also occurs if the application of ttac fails, after stripping the goal.
- USES
- PSTRIP_GOAL_THEN is used when manipulating intermediate results (obtained by stripping outer connectives from a goal) directly, rather than as assumptions.
- SEEALSO

HOL Kananaskis-14