Consider the following premises. forall x_21: P_21(x_21) -> S_2(x_21). forall x_21: Q_21(x_21) -> S_2(x_21). forall x_21: S_2(x_21) <-> S(x_21). forall x_21: P_21(x_21) or Q_21(x_21). Can we infer u from them?
We cannot infer that from the premises. Therefore the answer is no.