Consider the following premises. forall x_5: P_6(x_5) -> S_5(x_5). forall x_6: P_6(x_6). Can we infer S_5(a_6) from them?
 From forall x_6: P_6(x_6) we can infer P_6(a_6). From forall x_5: P_6(x_5) -> S_5(x_5) we can infer P_6(a_6) -> S_5(a_6). Finally, from P_6(a_6) -> S_5(a_6), P_6(a_6) we can infer S_5(a_6). Therefore, the answer is yes.