Dave is not round. Fiona is blue. Fiona is green. Fiona is smart. Gary is big. Gary is green. Gary is smart. If Gary is green then Gary is blue. If Fiona is green then Fiona is round. If something is smart then it is big. Big, smart things are green. If something is not round and not blue then it is smart. If Gary is not round and Gary is not blue then Gary is green.
Dave is not green.