Consider the following premises. u <-> w. u or ~q_2. w or q_2. Can we infer u from them? If possible, name the inference rules being used at each step.
 From u <-> w we can infer w -> u via biconditional elimination. From u or ~q_2 we can infer q_2 -> u via rewriting. Finally, from w -> u, q_2 -> u, w or q_2 we can infer u via disjunction elimination. Therefore, the answer is yes.