Consider the following premises. forall x_18: P_18(x_18) <-> Q_18(x_18). forall x_18: ~Q_18(x_18). forall x_18: P_18(x_18) or Q_12(x_18). Can we infer forall y: ~(Q_12(y) or T_1(y)) from them? If possible, name the inference rules being used at each step.
That contradicts the premises. Therefore the answer is no.