Charlie is green. Charlie is quiet. Charlie is round. Charlie is young. Dave is furry. Dave is not green. Dave is round. Dave is not smart. Fiona is green. Fiona is smart. If someone is green and not round then they are young. If someone is smart and young then they are not furry. If Charlie is quiet and Charlie is young then Charlie is not smart. If Charlie is quiet then Charlie is cold. If someone is not furry and not cold then they are young. If someone is round and not young then they are not quiet.
Dave is not young.