Consider the following premises. forall x_18: P_18(x_18) <-> Q(x_18). forall x_18: Q_14(x_18) -> Q(x_18). forall x_18: P_18(x_18). Can we infer ~Q(b) from them?
 From forall x_18: P_18(x_18) <-> Q(x_18) we can infer forall x_18: P_18(x_18) -> Q(x_18). From forall x_18: P_18(x_18) we can infer forall x_18: P_18(x_18) or Q_14(x_18). Finally, from forall x_18: P_18(x_18) -> Q(x_18), forall x_18: Q_14(x_18) -> Q(x_18), forall x_18: P_18(x_18) or Q_14(x_18) we can infer forall x_18: Q(x_18), which contradicts ~Q(b). Therefore, the answer is no.