Consider the following premises. forall y_3: ~Q(y_3). exists y_3: P(y_3) <-> T(y_3). forall y_3: Q(y_3) <-> T(y_3). Can we infer forall y_3: Q(y_3) <-> T(y_3) from them?
That is one of the premises. Therefore, the answer is yes.