Returns result of first tactic, if there is any, else it returns the result of the second tactic, with the possibility of no result from either.
Returns result of first tactic, if there is any, else it returns the result of the second tactic, with the possibility of no result from either.
Returns result of first tactical, if there is any, else it returns the result of the second tactical, with the possibility of no result from either.
Returns result of first tactical, if there is any, else it returns the result of the second tactical, with the possibility of no result from either.
Calls prover9 on the subgoal.