Consider the following premises. q_13 or r_2. r_2 -> p_1. p_1 <-> q_13. Can we infer p_1 or u from them?
 From p_1 <-> q_13 we can infer q_13 -> p_1. From q_13 -> p_1, r_2 -> p_1, q_13 or r_2 we can infer p_1. Finally, from p_1 we can infer p_1 or u. Therefore, the answer is yes.