Consider the following premises. p_11 <-> q_11. q_2. q_2 <-> q_11. Can we infer q_11 from them?
 From p_11 <-> q_11 we can infer p_11 -> q_11. From q_2 we can infer q_2 or p_11. From q_2 <-> q_11 we can infer q_2 -> q_11. Finally, from q_2 -> q_11, p_11 -> q_11, q_2 or p_11 we can infer q_11. Therefore, the answer is yes.