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) or U_2(x). exists x: ~R_1(x). forall x: R_1(x) <-> U_2(x). forall x: ~U(x) or W(x).
forall x: U_2(x) or W(x). forall x: R_1(x) -> U_2(x). forall x: U_2(x) -> R_1(x). exists x: ~U_2(x).