Consider the following premises. q_4 <-> q. w <-> r. ~w. q_4 -> r. Can we infer q from them?
 From w <-> r, ~w we can infer ~r. From q_4 -> r, ~r we can infer ~q_4. Finally, from q_4 <-> q, ~q_4 we can infer ~q, which contradicts q. Therefore, the answer is no.