Consider the following premises. t -> r. p_11 -> u_3. p_6 or t. ~u_3. p_6 -> r. Can we infer ~p_11 and r from them?
 From p_11 -> u_3, ~u_3 we can infer ~p_11. From p_6 -> r, t -> r, p_6 or t we can infer r. Finally, from ~p_11, r we can infer ~p_11 and r. Therefore, the answer is yes.