Consider the following premises. ~t. q <-> p_6. p_6 -> t. Can we infer q from them?
 From p_6 -> t, ~t we can infer ~p_6. From q <-> p_6 we can infer q -> p_6. Finally, from q -> p_6, ~p_6 we can infer ~q, which contradicts q. Therefore, the answer is no.