Consider the following premises. p_11 or ~s. ~p_4. p_4 or s. Can we infer ~p_11 from them?
 From p_11 or ~s we can infer s -> p_11. From p_4 or s, ~p_4 we can infer s. Finally, from s -> p_11, s we can infer p_11, which contradicts ~p_11. Therefore, the answer is no.