What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? exists z_2: ~U(z_2) or P_4(z_2). forall z_2: U(z_2) or S(z_2). forall z_2: ~S(z_2).
exists z_2: S(z_2) or P_4(z_2).