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 -> w_1. q_1 -> u. w_2 -> q_1. u -> u_1.
q_1 -> u_1 can be inferred via the transitivity rule. w_2 -> u can be inferred via the transitivity rule. u -> w_1 can be inferred via the transitivity rule.