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