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_11(x_18) -> Q_18(x_18). forall x_18: Q(x_18). forall x_18: P_18(x_18) <-> Q_18(x_18). exists x_18: P_11(x_18) or P_12(x_18). forall x_18: P_12(x_18) -> P_18(x_18).
forall x_18: P_18(x_18) -> Q_18(x_18). forall x_18: Q_18(x_18) -> P_18(x_18).