Consider the following premises. forall x_17: R_4(x_17) -> S_17(x_17). r_1 <-> R_4(a_17). R_4(a_17) -> r_1. Can we infer r_1 -> S_17(a_17) from them?
 From forall x_17: R_4(x_17) -> S_17(x_17) we can infer R_4(a_17) -> S_17(a_17). From r_1 <-> R_4(a_17) we can infer r_1 -> R_4(a_17). From R_4(a_17) -> r_1, r_1 -> R_4(a_17) we can infer R_4(a_17) <-> r_1. From R_4(a_17) <-> r_1 we can infer r_1 -> R_4(a_17). Finally, from r_1 -> R_4(a_17), R_4(a_17) -> S_17(a_17) we can infer r_1 -> S_17(a_17). Therefore, the answer is yes.