Consider the following premises. forall x_17: U(x_17) -> S_17(x_17). p_8 -> U(a_3). S_17(a_3) <-> p_8. Can we infer p_8 -> S_17(a_3) from them?
 From forall x_17: U(x_17) -> S_17(x_17) we can infer U(a_3) -> S_17(a_3). Finally, from p_8 -> U(a_3), U(a_3) -> S_17(a_3) we can infer p_8 -> S_17(a_3). Therefore, the answer is yes.