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