Let isa = direct-isa be the transitive, re exive closure of direct-isa, so that c 0 ; c 2 isa c is a hypernym of c 0 ; and let c = f c 0 jc 0 ; c 2 isa g be the set consisting of the concept c and all of its hyponyms.
the set hfoodi contains all the concepts which are kinds of food, including hfoodi.