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