Consider the following premises. forall x: U(x) <-> T(x). forall x: ~R_3(x). forall x: R_3(x) <-> U(x). Can we infer exists x: T(x) from them?
 From forall x: R_3(x) <-> U(x), forall x: ~R_3(x) we can infer forall x: ~U(x). Finally, from forall x: U(x) <-> T(x), forall x: ~U(x) we can infer forall x: ~T(x), which contradicts exists x: T(x). Therefore, the answer is no.