Consider the following premises. t -> r_4. p_7 <-> r_4. p_7 -> ~s_3. s_3. Can we infer ~t from them? If possible, name the inference rules being used at each step.
 From p_7 -> ~s_3, s_3 we can infer ~p_7 via modus tollens. From p_7 <-> r_4, ~p_7 we can infer ~r_4 via biconditional elimination. Finally, from t -> r_4, ~r_4 we can infer ~t via modus tollens. Therefore, the answer is yes.