Consider the following premises. u -> ~R_15(a_9). forall x_15: ~Q_15(x_15). forall x_15: ~P_15(x_15) or R_15(x_15). forall x_15: P_15(x_15) or Q_15(x_15). Can we infer ~u from them?
 From forall x_15: P_15(x_15) or Q_15(x_15), forall x_15: ~P_15(x_15) or R_15(x_15) we can infer forall x_15: Q_15(x_15) or R_15(x_15). From forall x_15: Q_15(x_15) or R_15(x_15), forall x_15: ~Q_15(x_15) we can infer forall x_15: R_15(x_15). From forall x_15: R_15(x_15) we can infer R_15(a_9). Finally, from u -> ~R_15(a_9), R_15(a_9) we can infer ~u. Therefore, the answer is yes.