Consider the following premises. s_1 or ~p_3. r or ~s_1. r -> p_3. Can we infer r <-> s_1 from them?
 From s_1 or ~p_3 we can infer p_3 -> s_1. From r -> p_3, p_3 -> s_1 we can infer r -> s_1. From r or ~s_1 we can infer s_1 -> r. Finally, from r -> s_1, s_1 -> r we can infer r <-> s_1. Therefore, the answer is yes.