Consider the following premises. q <-> q_14. ~q_14. w <-> t_4. t_4 -> q. Can we infer w from them? If possible, name the inference rules being used at each step.
 From q <-> q_14, ~q_14 we can infer ~q via biconditional elimination. From t_4 -> q, ~q we can infer ~t_4 via modus tollens. From w <-> t_4 we can infer w -> t_4 via biconditional elimination. Finally, from w -> t_4, ~t_4 we can infer ~w via modus tollens, which contradicts w. Therefore, the answer is no.