Consider the following premises. p_7 <-> q. ~t or u. t or q. u -> p_7. Can we infer ~p_7 from them? If possible, name the inference rules being used at each step.
 From p_7 <-> q we can infer q -> p_7 via biconditional elimination. From t or q, ~t or u we can infer q or u via resolution. Finally, from q -> p_7, u -> p_7, q or u we can infer p_7 via disjunction elimination, which contradicts ~p_7. Therefore, the answer is no.