Consider the following premises. t_4 -> p_4. w_1 <-> u. ~u. p_4 <-> w_1. Can we infer ~t_4 from them? If possible, name the inference rules being used at each step.
 From w_1 <-> u, ~u we can infer ~w_1 via biconditional elimination. From p_4 <-> w_1, ~w_1 we can infer ~p_4 via biconditional elimination. Finally, from t_4 -> p_4, ~p_4 we can infer ~t_4 via modus tollens. Therefore, the answer is yes.