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: s_1 or s. ~s_1. p_4 or u_1. ~p_4.
s can be inferred via the disjunctive syllogism rule. u_1 can be inferred via the disjunctive syllogism rule. ~s_1 and ~p_4 can be inferred via the conjunction rule. ~p_4 and ~s_1 can be inferred via the conjunction rule.