CHOOSE_TAC : thm_tactic
A ?- u ==================== CHOOSE_TAC (A' |- ?x. t) A u {t[x'/x]} ?- uUnless A' is a subset of A, this is not a valid tactic.
?- ?t. output(t)and we have the following theorems available:
t1 = |- ?t. input(t) t2 = !t. input(t) ==> output(t+1)Then the goal can be solved by the application of:
CHOOSE_TAC th1 THEN EXISTS_TAC (Term `t+1`) THEN UNDISCH_TAC (Term `input (t:num) :bool`) THEN MATCH_ACCEPT_TAC th2