Consider the following premises. forall x_15: P_15(x_15) and Q_15(x_15). ~P_15(a). Can we infer u from them?
 From forall x_15: P_15(x_15) and Q_15(x_15) we can infer forall x_15: P_15(x_15). From forall x_15: P_15(x_15) we can infer P_15(a). From P_15(a) we can infer P_15(a) or u. Finally, from P_15(a) or u, ~P_15(a) we can infer u. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.