Consider the following premises. q_15 -> p. u <-> q_15. ~u. u or ~p. Can we infer p from them? If possible, name the inference rules being used at each step.
 From u <-> q_15 we can infer u -> q_15 via biconditional elimination. From u -> q_15, q_15 -> p we can infer u -> p via transitivity. From u or ~p we can infer p -> u via rewriting. From p -> u, u -> p we can infer p <-> u via biconditional introduction. Finally, from p <-> u, ~u we can infer ~p via biconditional elimination, which contradicts p. Therefore, the answer is no.