Consider the following premises. t_3. t_4 or q. q_19. ~t_4. Can we infer ~q from them? If possible, name the inference rules being used at each step.
 From t_3, q_19 we can infer t_3 and q_19 via conjunction. Finally, from t_4 or q, ~t_4 we can infer q via disjunctive syllogism, which contradicts ~q. Therefore, the answer is no.