Consider the following premises. q_2. p_6 -> ~q_2. w_4 -> p_6. p_6 -> w_4. Can we infer w_4 from them? If possible, name the inference rules being used at each step.
 From p_6 -> w_4, w_4 -> p_6 we can infer p_6 <-> w_4 via biconditional introduction. From p_6 -> ~q_2, q_2 we can infer ~p_6 via modus tollens. Finally, from p_6 <-> w_4, ~p_6 we can infer ~w_4 via biconditional elimination, which contradicts w_4. Therefore, the answer is no.