Consider the following premises. forall y_4: R_3(y_4) <-> Q_7(y_4). forall y_4: R_3(y_4). Can we infer Q_7(a) from them?
 From forall y_4: R_3(y_4) <-> Q_7(y_4) we can infer forall y_4: R_3(y_4) -> Q_7(y_4). From forall y_4: R_3(y_4) -> Q_7(y_4), forall y_4: R_3(y_4) we can infer forall y_4: Q_7(y_4). Finally, from forall y_4: Q_7(y_4) we can infer Q_7(a). Therefore, the answer is yes.