Consider the following premises. ~w. p -> r_4. w or ~r_4. Can we infer p from them?
 From w or ~r_4 we can infer r_4 -> w. From r_4 -> w, ~w we can infer ~r_4. Finally, from p -> r_4, ~r_4 we can infer ~p, which contradicts p. Therefore, the answer is no.