Dave is young. Erin is quiet. Erin is young. Fiona is nice. Fiona is smart. Harry is green. Harry is red. All green, young people are quiet. All smart people are rough. If someone is rough then they are green. All young people are red. All smart, rough people are red. Young people are nice. All young, red people are smart. If someone is rough then they are green.
Dave is not smart.