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: w_4 -> u. w_4 or q_9. u or ~q_9. u -> q_9.
w_4 -> q_9 can be inferred via the transitivity rule. q_9 -> u can be inferred via the rewriting rule.