Consider the following premises. p_12 or ~w. r -> w. t_4 <-> p_12. t_4 or r. Can we infer p_12 from them?
 From p_12 or ~w we can infer w -> p_12. From r -> w, w -> p_12 we can infer r -> p_12. From t_4 <-> p_12 we can infer t_4 -> p_12. Finally, from t_4 -> p_12, r -> p_12, t_4 or r we can infer p_12. Therefore, the answer is yes.