Consider the following premises. p_4 -> r_4. ~r_1 or p_4. q_2 or r_1. s_1 -> r_4. ~q_2 or s_1. Can we infer r_4 or q_1 from them? If possible, name the inference rules being used at each step.
 From q_2 or r_1, ~q_2 or s_1 we can infer r_1 or s_1 via resolution. From r_1 or s_1, ~r_1 or p_4 we can infer s_1 or p_4 via resolution. From s_1 -> r_4, p_4 -> r_4, s_1 or p_4 we can infer r_4 via disjunction elimination. Finally, from r_4 we can infer r_4 or q_1 via addition. Therefore, the answer is yes.