What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall x: P_3(x) -> S(x). exists x: ~P_3(x). forall x: S(x) or U_2(x). forall x: W_4(x). forall x: S(x) -> P_3(x).
exists x: ~S(x). forall x: P_3(x) <-> S(x). forall x: S(x) <-> P_3(x).