Consider the following premises. p. p_11 or ~s. p_11 <-> p_14. p_14 -> ~p. p_11 -> s. Can we infer ~s from them?
 From p_14 -> ~p, p we can infer ~p_14. From p_11 <-> p_14, ~p_14 we can infer ~p_11. From p_11 or ~s we can infer s -> p_11. From p_11 -> s, s -> p_11 we can infer p_11 <-> s. Finally, from p_11 <-> s, ~p_11 we can infer ~s. Therefore, the answer is yes.