Consider the following premises. u_2 <-> q. u <-> s. s <-> u_2. ~u. Can we infer ~q from them?
 From u <-> s, ~u we can infer ~s. From s <-> u_2, ~s we can infer ~u_2. Finally, from u_2 <-> q, ~u_2 we can infer ~q. Therefore, the answer is yes.