Consider the following premises. David is a police officer and William is an artist. If Karen climbs a mountain, then Charles is playing squash. David is not a police officer or James is a janitor. If James were a janitor, then Charles is playing squash. Can we infer the following from them? If we can, name the inference rule being used: Charles is not playing squash.
 From the fact that David is a police officer and William is an artist we can infer that David is a police officer via simplification. From the fact that David is a police officer we can infer that David is a police officer or Karen is climbing a mountain via addition. From the fact that David is a police officer or Karen is climbing a mountain, and that David is not a police officer or James is a janitor we can infer that Karen is climbing a mountain or James is a janitor via resolution. Finally, from the fact that if Karen climbs a mountain, then Charles is playing squash, that if James were a janitor, then Charles is playing squash, and that Karen is climbing a mountain or James is a janitor we can infer that Charles is playing squash via disjunction elimination, which contradicts that Charles is not playing squash. Therefore, the answer is no.