Consider the following premises. forall y: U(y) -> R(y). forall y: U(y) or ~R(y). Can we infer exists y: ~(R(y) <-> U(y)) from them?
 From forall y: U(y) or ~R(y) we can infer forall y: R(y) -> U(y). Finally, from forall y: R(y) -> U(y), forall y: U(y) -> R(y) we can infer forall y: R(y) <-> U(y), which contradicts exists y: ~(R(y) <-> U(y)). Therefore, the answer is no.