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_1 -> p_3. ~p_3. u -> u_1. p_3 -> u.
~u_1 can be inferred via the modus tollens rule. u_1 -> u can be inferred via the transitivity rule. u -> p_3 can be inferred via the transitivity rule. p_3 -> u_1 can be inferred via the transitivity rule.