Consider the following premises. exists y_3: ~P(y_3). forall y_3: T(y_3) -> P(y_3). forall y_3: T(y_3) <-> P(y_3). Can we infer forall y_3: T(y_3) from them?
 From forall y_3: T(y_3) <-> P(y_3) we can infer forall y_3: P(y_3) -> T(y_3). From forall y_3: T(y_3) -> P(y_3), forall y_3: P(y_3) -> T(y_3) we can infer forall y_3: T(y_3) <-> P(y_3). Finally, from forall y_3: T(y_3) <-> P(y_3), exists y_3: ~P(y_3) we can infer exists y_3: ~T(y_3), which contradicts forall y_3: T(y_3). Therefore, the answer is no.