Consider the following premises. p -> r_8. ~q_4. w <-> q_4. r_8 -> w. w -> p. Can we infer ~r_8 from them?
 From w -> p, p -> r_8 we can infer w -> r_8. From w -> r_8, r_8 -> w we can infer w <-> r_8. From w <-> q_4, ~q_4 we can infer ~w. Finally, from w <-> r_8, ~w we can infer ~r_8. Therefore, the answer is yes.