What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: ~q_1. p -> q_1. p <-> q_1. ~p -> t_1.
~p can be inferred via the modus tollens rule. p -> q_1 can be inferred via the biconditional elimination rule. q_1 -> p can be inferred via the biconditional elimination rule. ~p can be inferred via the biconditional elimination rule.