What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall z_1: S_4(z_1) -> R_2(z_1). forall z_1: S_4(z_1) or U(z_1). exists z_1: U(z_1) -> R_2(z_1). forall z_1: R_2(z_1) -> S_4(z_1).
exists z_1: U(z_1) -> S_4(z_1). exists z_1: R_2(z_1). forall z_1: S_4(z_1) <-> R_2(z_1). forall z_1: R_2(z_1) <-> S_4(z_1).