What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? exists z_1: U_2(z_1) -> U(z_1). forall z_1: P_4(z_1) -> U_2(z_1). forall z_1: ~P_4(z_1). forall z_1: U_2(z_1) <-> U(z_1). forall z_1: U_2(z_1) -> P_4(z_1).
forall z_1: ~U_2(z_1). exists z_1: P_4(z_1) -> U(z_1). forall z_1: P_4(z_1) <-> U_2(z_1). forall z_1: U_2(z_1) <-> P_4(z_1). forall z_1: U_2(z_1) -> U(z_1). forall z_1: U(z_1) -> U_2(z_1).