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