What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall z: U(z) -> U_2(z). forall z: U_2(z). forall z: U_2(z) -> U(z).
forall z: U(z). forall z: U(z) <-> U_2(z). forall z: U_2(z) <-> U(z).