Consider the following premises. forall x_18: ~Q_18(x_18). forall x_18: P_18(x_18) <-> Q_18(x_18). P_18(a_14) <-> t. Can we infer t from them?
 From forall x_18: P_18(x_18) <-> Q_18(x_18), forall x_18: ~Q_18(x_18) we can infer forall x_18: ~P_18(x_18). From forall x_18: ~P_18(x_18) we can infer ~P_18(a_14). Finally, from P_18(a_14) <-> t, ~P_18(a_14) we can infer ~t, which contradicts t. Therefore, the answer is no.