Consider the following premises. ~q_3. u_3 -> s_1. s_1 -> q_3. u_3 <-> q. Can we infer ~q from them? If possible, name the inference rules being used at each step.
 From s_1 -> q_3, ~q_3 we can infer ~s_1 via modus tollens. From u_3 -> s_1, ~s_1 we can infer ~u_3 via modus tollens. Finally, from u_3 <-> q, ~u_3 we can infer ~q via biconditional elimination. Therefore, the answer is yes.