Consider the following premises. forall z_2: R(z_2) <-> S_4(z_2). forall z_2: Q(z_2) -> S_4(z_2). exists z_2: R(z_2) or T(z_2). forall z_2: T(z_2) -> Q(z_2). Can we infer exists z_2: S_4(z_2) from them?
 From forall z_2: R(z_2) <-> S_4(z_2) we can infer forall z_2: R(z_2) -> S_4(z_2). From forall z_2: T(z_2) -> Q(z_2), forall z_2: Q(z_2) -> S_4(z_2) we can infer forall z_2: T(z_2) -> S_4(z_2). Finally, from forall z_2: R(z_2) -> S_4(z_2), forall z_2: T(z_2) -> S_4(z_2), exists z_2: R(z_2) or T(z_2) we can infer exists z_2: S_4(z_2). Therefore, the answer is yes.