Consider the following premises. u_1 -> ~q_11. w_3 -> u_1. q_11. q. Can we infer w_3 from them? If possible, name the inference rules being used at each step.
 From u_1 -> ~q_11, q_11 we can infer ~u_1 via modus tollens. Finally, from w_3 -> u_1, ~u_1 we can infer ~w_3 via modus tollens, which contradicts w_3. Therefore, the answer is no.