Consider the following premises. forall x_10: P_10(x_10) -> Q_10(x_10). forall x_10: ~Q_10(x_10). forall x_10: P_9(x_10) <-> P_10(x_10). u -> P_9(a_5). Can we infer u from them?
 From forall x_10: P_10(x_10) -> Q_10(x_10), forall x_10: ~Q_10(x_10) we can infer forall x_10: ~P_10(x_10). From forall x_10: P_9(x_10) <-> P_10(x_10), forall x_10: ~P_10(x_10) we can infer forall x_10: ~P_9(x_10). From forall x_10: ~P_9(x_10) we can infer ~P_9(a_5). Finally, from u -> P_9(a_5), ~P_9(a_5) we can infer ~u, which contradicts u. Therefore, the answer is no.