Consider the following premises. w -> q_19. ~w -> t_3. ~u. t_3 -> q. q_19 -> u. Can we infer ~q from them? If possible, name the inference rules being used at each step.
 From w -> q_19, q_19 -> u we can infer w -> u via transitivity. From w -> u, ~u we can infer ~w via modus tollens. From ~w -> t_3, ~w we can infer t_3 via modus ponens. Finally, from t_3 -> q, t_3 we can infer q via modus ponens, which contradicts ~q. Therefore, the answer is no.