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: ~p_2 -> t_4. t -> p_2. ~t. p_2 -> t.
~p_2 can be inferred via the modus tollens rule. t <-> p_2 can be inferred via the biconditional introduction rule. p_2 <-> t can be inferred via the biconditional introduction rule.