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: u -> p_3. ~u. p_3 -> p. p -> u.
~p can be inferred via the modus tollens rule. u -> p can be inferred via the transitivity rule. p_3 -> u can be inferred via the transitivity rule. p -> p_3 can be inferred via the transitivity rule.