John F. Horty, Richmond H. Thomason
Much of the theoretical research on nonmonotonic inheritance has concentrated on formalisms involving only IS-A links between primitive nodes. However, it is hard to imagine a useful network representation of commonsense or expert knowledge that would not involve nodes representing negative, conjunctive, or disjunctive properties. Certain nodes of this kind were included in some of the earliest formalisms for defeasible inheritance, but were omitted in later work, either to secure tractability or to simplify the task of theoretical analysis. The purpose of the present paper is to extend the theoretical analysis of defeasible inheritance to networks incorporating these expressive enhancements.