What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall z: S_2(z) -> W(z). forall z: W(z) -> S_2(z). S_2(f_4).
exists x: S_2(x). forall z: S_2(z) <-> W(z). forall z: W(z) <-> S_2(z).