What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall z: T(z) -> S_4(z). exists z: S_4(z) -> T(z). forall z: T(z) -> S_4(z).
exists z: S_4(z) <-> T(z). exists z: S_4(z) <-> T(z). exists z: T(z) <-> S_4(z). exists z: T(z) <-> S_4(z).