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: q_7 -> r. ~t_1 or u. q_4 -> r. u -> q_4. t_1 or q_7.
u -> r can be inferred via the transitivity rule. q_7 or u can be inferred via the resolution rule.