Implicit Ordering Of Defaults In Inheritance Systems

Abstract

There is a natural partial ordering of defaults in inheritance systems that resolves ambiguities in an intuitive way. This is not the shortest-path ordering used by most existing inheritance reasoners. The flaws of the shortest-path ordering become apparent when we consider multiple inheritance. We define the correct partial ordering to use in inheritance and show how it applies to semantic network systems. Use of this ordering also simplifies the representation of inheritance in default logic.