Consider the following premises. t_3. p_9 -> p_5. p_5 <-> p_9. p_9 -> ~t_3. Can we infer p_5 from them? If possible, name the inference rules being used at each step.
 From p_9 -> ~t_3, t_3 we can infer ~p_9 via modus tollens. From p_5 <-> p_9 we can infer p_5 -> p_9 via biconditional elimination. From p_5 -> p_9, p_9 -> p_5 we can infer p_5 <-> p_9 via biconditional introduction. Finally, from p_5 <-> p_9, ~p_9 we can infer ~p_5 via biconditional elimination, which contradicts p_5. Therefore, the answer is no.