Consider the following premises. r_1. p. ~r_1. Can we infer q_12 from them?
 From r_1 we can infer r_1 or q_12. Finally, from r_1 or q_12, ~r_1 we can infer q_12. Therefore, the answer is yes. Notice, however, that the premises were contradictory, so we can infer anything from them.