Bob is not blue. Bob is cold. Bob is quiet. Bob is red. Bob is rough. Bob is round. Bob is smart. Dave is cold. Dave is red. Dave is not rough. All red, blue things are not rough. If something is cold then it is red. If something is quiet and not round then it is rough. If something is cold and not round then it is blue. If something is not blue and not cold then it is red. If something is round and not red then it is smart.
Dave is not blue.