Consider the following premises. q. r_4 <-> w. ~w_2. r_4 <-> w_2. Can we infer w from them?
 From r_4 <-> w_2, ~w_2 we can infer ~r_4. Finally, from r_4 <-> w, ~r_4 we can infer ~w, which contradicts w. Therefore, the answer is no.