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