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