What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall z: P_1(z) <-> U(z). forall z: U(z) <-> P_1(z).
forall z: P_1(z) -> U(z). forall z: U(z) -> P_1(z). forall z: U(z) -> P_1(z). forall z: P_1(z) -> U(z).