Consider the following premises. forall x_11: P_11(x_11) and Q_11(x_11). forall x_11: T(x_11) -> ~P_11(x_11). exists x_11: U(x_11) <-> S(x_11). forall x_11: T(x_11) <-> U(x_11). Can we infer forall x_11: S(x_11) from them?
 From forall x_11: P_11(x_11) and Q_11(x_11) we can infer forall x_11: P_11(x_11). From forall x_11: T(x_11) -> ~P_11(x_11), forall x_11: P_11(x_11) we can infer forall x_11: ~T(x_11). From forall x_11: T(x_11) <-> U(x_11), forall x_11: ~T(x_11) we can infer forall x_11: ~U(x_11). Finally, from exists x_11: U(x_11) <-> S(x_11), forall x_11: ~U(x_11) we can infer exists x_11: ~S(x_11), which contradicts forall x_11: S(x_11). Therefore, the answer is no.