What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? exists z: U(z) -> P_3(z). forall z: R_4(z) -> U(z). forall z: R_4(z) <-> P_3(z).
exists z: R_4(z) -> P_3(z). forall z: R_4(z) -> P_3(z). forall z: P_3(z) -> R_4(z).