Consider the following premises. w_3 or ~q_9. w_3 <-> q_9. Can we infer ~(w_3 -> q_9) from them? If possible, name the inference rules being used at each step.
 From w_3 or ~q_9 we can infer q_9 -> w_3 via rewriting. Finally, from w_3 <-> q_9 we can infer w_3 -> q_9 via biconditional elimination, which contradicts ~(w_3 -> q_9). Therefore, the answer is no.