What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? exists z: R(z) -> ~S_2(z). forall z: R(z) -> Q(z). forall z: Q(z) -> R(z). forall z: S_2(z).
exists z: ~R(z). forall z: R(z) <-> Q(z). forall z: Q(z) <-> R(z).