Bob is green. Bob is nice. Dave is white. Gary is green. Gary is nice. Gary is quiet. Gary is young. All quiet things are nice. If something is not round then it is white. All white things are green. All round things are young. All blue things are young. All white, nice things are blue. If Bob is quiet and Bob is not green then Bob is not nice. If Bob is round and Bob is not nice then Bob is not young.
Dave is not young.