Consider the following premises. p_1 <-> r_3. p_1 or ~r_3. Can we infer p_1 -> r_3 from them?
 From p_1 or ~r_3 we can infer r_3 -> p_1. Finally, from p_1 <-> r_3 we can infer p_1 -> r_3. Therefore, the answer is yes.