Consider the following premises. w_4 -> t_2. t_2 or q. w_4 <-> t_2. q -> w_4. Can we infer w_4 from them?
 From w_4 <-> t_2 we can infer t_2 -> w_4. From w_4 -> t_2, t_2 -> w_4 we can infer w_4 <-> t_2. From w_4 <-> t_2 we can infer t_2 -> w_4. Finally, from t_2 -> w_4, q -> w_4, t_2 or q we can infer w_4. Therefore, the answer is yes.