Bob is not big. Bob is white. Charlie is blue. Charlie is green. Charlie is young. Dave is big. Dave is blue. Dave is not green. Dave is white. Gary is not green. All green, young things are blue. Furry things are big. Green things are white. If something is green then it is furry. Round things are young. If Dave is young and Dave is not round then Dave is not white. If something is not big then it is young. If something is round and not white then it is not furry.
Dave is not blue.