Consider the following premises. Q(a_5) <-> u. forall x_15: ~T_2(x_15). forall x_15: U_4(x_15) <-> Q(x_15). forall x_15: T_2(x_15) or ~U_4(x_15). Can we infer ~u from them?
 From forall x_15: T_2(x_15) or ~U_4(x_15) we can infer forall x_15: U_4(x_15) -> T_2(x_15). From forall x_15: U_4(x_15) -> T_2(x_15), forall x_15: ~T_2(x_15) we can infer forall x_15: ~U_4(x_15). From forall x_15: U_4(x_15) <-> Q(x_15), forall x_15: ~U_4(x_15) we can infer forall x_15: ~Q(x_15). From forall x_15: ~Q(x_15) we can infer ~Q(a_5). Finally, from Q(a_5) <-> u, ~Q(a_5) we can infer ~u. Therefore, the answer is yes.