Consider the following premises. ~u_1. u_1 -> p_2. p <-> p_2. p_2 -> u_1. Can we infer ~p from them?
 From p_2 -> u_1, u_1 -> p_2 we can infer p_2 <-> u_1. From p_2 <-> u_1, ~u_1 we can infer ~p_2. Finally, from p <-> p_2, ~p_2 we can infer ~p. Therefore, the answer is yes.