Consider the following premises. s_1 -> r_1. s_2 or q. s_2 -> ~r_1. s_1 or r_4. r_4 -> r_1. Can we infer q from them? If possible, name the inference rules being used at each step.
 From s_1 -> r_1, r_4 -> r_1, s_1 or r_4 we can infer r_1 via disjunction elimination. From s_2 -> ~r_1, r_1 we can infer ~s_2 via modus tollens. Finally, from s_2 or q, ~s_2 we can infer q via disjunctive syllogism. Therefore, the answer is yes.