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_2 -> P_4(a_14). forall x_20: P_4(x_20) -> ~S_2(x_20). forall x_20: ~P_20(x_20). forall x_20: P_20(x_20) or S_2(x_20).
forall x_20: S_2(x_20) can be inferred via the universal disjunctive syllogism rule.