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_3 -> q. p -> p_3. q -> p. ~p.
~q can be inferred via the modus tollens rule. p_3 -> p can be inferred via the transitivity rule. p -> q can be inferred via the transitivity rule. q -> p_3 can be inferred via the transitivity rule.