Consider the following premises. forall x_25: P_25(x_25). forall z_3: P(z_3). forall x_25: P_25(x_25) <-> Q_25(x_25). Can we infer P(a_18) and Q_25(a_9) from them?
 From forall x_25: P_25(x_25) <-> Q_25(x_25) we can infer forall x_25: P_25(x_25) -> Q_25(x_25). From forall x_25: P_25(x_25) -> Q_25(x_25), forall x_25: P_25(x_25) we can infer forall x_25: Q_25(x_25). From forall z_3: P(z_3) we can infer P(a_18). From forall x_25: Q_25(x_25) we can infer Q_25(a_9). Finally, from P(a_18), Q_25(a_9) we can infer P(a_18) and Q_25(a_9). Therefore, the answer is yes.