What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? exists z: P(z) -> R(z). forall z: P_2(z) or ~Q(z). forall z: Q(z) <-> R(z).
forall z: Q(z) -> P_2(z). forall z: Q(z) -> R(z). forall z: R(z) -> Q(z).