What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall x_15: P_15(x_15) <-> Q_15(x_15). s -> P_15(a_11). forall x_15: Q_15(x_15) -> P_15(x_15). ~Q_15(a_11).
forall x_15: P_15(x_15) -> Q_15(x_15). forall x_15: Q_15(x_15) -> P_15(x_15).