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_6 -> u_4. p -> q_6. r_2 or ~s. r_2 -> p.
p -> u_4 can be inferred via the transitivity rule. r_2 -> q_6 can be inferred via the transitivity rule. s -> r_2 can be inferred via the rewriting rule.