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