Consider the following premises. forall y_1: Q_2(y_1) <-> P(y_1). forall y_1: ~Q_2(y_1). u -> P(d). Can we infer ~u or t_4 from them?
 From forall y_1: Q_2(y_1) <-> P(y_1), forall y_1: ~Q_2(y_1) we can infer forall y_1: ~P(y_1). From forall y_1: ~P(y_1) we can infer ~P(d). From u -> P(d), ~P(d) we can infer ~u. Finally, from ~u we can infer ~u or t_4. Therefore, the answer is yes.