Consider the following premises. p or ~q_12. u or ~p. u -> q_12. Can we infer u <-> p from them?
 From p or ~q_12 we can infer q_12 -> p. From u -> q_12, q_12 -> p we can infer u -> p. From u or ~p we can infer p -> u. Finally, from u -> p, p -> u we can infer u <-> p. Therefore, the answer is yes.