Consider the following premises. forall x_1: R(x_1) -> U(x_1). exists x_1: U(x_1) -> R(x_1). forall x_1: U(x_1) -> R(x_1). Can we infer forall x_1: ~(U(x_1) <-> R(x_1)) from them?
That contradicts the premises. Therefore the answer is no.