Consider the following premises. ~w_4 or r_12. r_12 <-> q_8. q_8 <-> t. w_4 or t. Can we infer q_8 from them? If possible, name the inference rules being used at each step.
 From w_4 or t, ~w_4 or r_12 we can infer t or r_12 via resolution. From r_12 <-> q_8 we can infer r_12 -> q_8 via biconditional elimination. From q_8 <-> t we can infer t -> q_8 via biconditional elimination. Finally, from t -> q_8, r_12 -> q_8, t or r_12 we can infer q_8 via disjunction elimination. Therefore, the answer is yes.