Consider the following premises. forall x_15: ~Q_15(x_15). forall x_15: P_15(x_15) -> Q_15(x_15). t_1 <-> P_15(a_14). Can we infer t_1 from them?
 From forall x_15: P_15(x_15) -> Q_15(x_15), forall x_15: ~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_14). Finally, from t_1 <-> P_15(a_14), ~P_15(a_14) we can infer ~t_1, which contradicts t_1. Therefore, the answer is no.