Consider the following premises. ~t_4. p_12 or ~s. w -> s. p_12 -> t_4. Can we infer w from them?
 From p_12 or ~s we can infer s -> p_12. From p_12 -> t_4, ~t_4 we can infer ~p_12. From w -> s, s -> p_12 we can infer w -> p_12. Finally, from w -> p_12, ~p_12 we can infer ~w, which contradicts w. Therefore, the answer is no.