Consider the following premises. t_4 <-> q_7. ~r. q -> r. q or ~q_7. Can we infer ~t_4 from them? If possible, name the inference rules being used at each step.
 From q -> r, ~r we can infer ~q via modus tollens. From q or ~q_7 we can infer q_7 -> q via rewriting. From q_7 -> q, ~q we can infer ~q_7 via modus tollens. Finally, from t_4 <-> q_7, ~q_7 we can infer ~t_4 via biconditional elimination. Therefore, the answer is yes.