Consider the following premises. exists z: S(z) -> R_4(z). forall z: R_4(z) -> ~U(z). forall z: U(z) and Q(z). Can we infer exists z: ~S(z) from them?
 From forall z: U(z) and Q(z) we can infer forall z: U(z). From forall z: R_4(z) -> ~U(z), forall z: U(z) we can infer forall z: ~R_4(z). Finally, from exists z: S(z) -> R_4(z), forall z: ~R_4(z) we can infer exists z: ~S(z). Therefore, the answer is yes.