MP_TACTactic.MP_TAC : thm_tactic
Reduces a goal to implication from a known theorem.
When applied to the theorem A' |- s and the goal
A ?- t, the tactic MP_TAC reduces the goal to
A ?- s ==> t. Unless A' is a subset of
A, this is an invalid tactic.
A ?- t
============== MP_TAC (A' |- s)
A ?- s ==> t
Never fails.