Consider the following premises. r -> ~p. t_4 -> q_11. ~q_11. p. Can we infer r from them? If possible, name the inference rules being used at each step.
 From t_4 -> q_11, ~q_11 we can infer ~t_4 via modus tollens. Finally, from r -> ~p, p we can infer ~r via modus tollens, which contradicts r. Therefore, the answer is no.