Consider the following premises. forall z_3: U(z_3) -> S_1(z_3). exists z_3: U_2(z_3) -> U(z_3). forall z_3: U_2(z_3) or ~S_1(z_3). forall z_3: ~T_4(z_3). forall z_3: U_2(z_3) <-> T_4(z_3). Can we infer forall z_3: U(z_3) from them?
 From forall z_3: U_2(z_3) <-> T_4(z_3), forall z_3: ~T_4(z_3) we can infer forall z_3: ~U_2(z_3). From forall z_3: U_2(z_3) or ~S_1(z_3) we can infer forall z_3: S_1(z_3) -> U_2(z_3). From forall z_3: U(z_3) -> S_1(z_3), forall z_3: S_1(z_3) -> U_2(z_3) we can infer forall z_3: U(z_3) -> U_2(z_3). From exists z_3: U_2(z_3) -> U(z_3), forall z_3: U(z_3) -> U_2(z_3) we can infer exists z_3: U_2(z_3) <-> U(z_3). Finally, from exists z_3: U_2(z_3) <-> U(z_3), forall z_3: ~U_2(z_3) we can infer exists z_3: ~U(z_3), which contradicts forall z_3: U(z_3). Therefore, the answer is no.