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: r_2 or u_4. p_1. ~r_2.
u_4 can be inferred via the disjunctive syllogism rule. p_1 and ~r_2 can be inferred via the conjunction rule. ~r_2 and p_1 can be inferred via the conjunction rule.