What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall x_13: ~Q_13(x_13). forall x_13: Q_9(x_13) -> S_2(x_13). forall x_13: S_2(x_13) <-> S_4(x_13). forall x_13: U(x_13) -> Q_9(x_13). exists x_13: S_4(x_13) -> Q_13(x_13).
exists x_13: ~S_4(x_13). forall x_13: U(x_13) -> S_2(x_13). forall x_13: S_2(x_13) -> S_4(x_13). forall x_13: S_4(x_13) -> S_2(x_13).