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