What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall x_18: P_18(x_18) -> U(x_18). forall x_18: P_4(x_18) -> U(x_18). forall x_18: P_4(x_18) or P_18(x_18). exists x_18: ~P_9(x_18). forall x_18: U(x_18) -> P_18(x_18). forall x_18: P_9(x_18) or W(x_18).
forall x_18: P_4(x_18) -> P_18(x_18). exists x_18: W(x_18). forall x_18: U(x_18). forall x_18: P_18(x_18) <-> U(x_18). forall x_18: U(x_18) <-> P_18(x_18).