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