Consider the following premises. w and q_17. p_1 -> ~w. p_1 -> p_6. p_6 -> p_1. Can we infer p_6 from them?
 From w and q_17 we can infer w. From p_1 -> ~w, w we can infer ~p_1. From p_6 -> p_1, p_1 -> p_6 we can infer p_6 <-> p_1. From p_6 <-> p_1 we can infer p_6 -> p_1. Finally, from p_6 -> p_1, ~p_1 we can infer ~p_6, which contradicts p_6. Therefore, the answer is no.