Consider the following premises. t_4 -> u. ~t. w -> t_4. q_3 <-> w. u -> t. Can we infer ~q_3 from them? If possible, name the inference rules being used at each step.
 From w -> t_4, t_4 -> u we can infer w -> u via transitivity. From w -> u, u -> t we can infer w -> t via transitivity. From w -> t, ~t we can infer ~w via modus tollens. Finally, from q_3 <-> w, ~w we can infer ~q_3 via biconditional elimination. Therefore, the answer is yes.