Consider the following premises. q <-> p. p -> w. q <-> u. ~w. Can we infer u from them?
 From q <-> p we can infer q -> p. From q -> p, p -> w we can infer q -> w. From q -> w, ~w we can infer ~q. From q <-> u we can infer u -> q. Finally, from u -> q, ~q we can infer ~u, which contradicts u. Therefore, the answer is no.