Consider the following premises. exists x_7: R_1(x_7) -> P_7(x_7). forall x_7: P_7(x_7) <-> Q_7(x_7). forall x_7: Q_7(x_7) -> R_1(x_7). Can we infer forall x_7: ~(R_1(x_7) <-> P_7(x_7)) from them?
That contradicts the premises. Therefore the answer is no.