Deriving and Retrieving Contextual Categorical Information through Instance Inheritance

In semantic and object oriented data models each class has one or more typing properties that associate it to other classes and carry type information about all instances of the class We introduce a new kind of property that we call instance typing property An instance typing property associates an instance of a class to another class and carries type information about that particular instance and not about all instances of the class Instance typing properties are important as they allow to represent summary information about an instance in addition to speci c information In this paper we study inheritance of properties from a class to an instance using type informa tion about the class as well as type information about the instance This kind of inheritance that we call contextual instance inheritance provides us with the most speci c type information about Research conducted while this author was visiting with the Institute of Computer Science Foundation for Research and Technology Hellas the instance in a particular context Intuitively a context is a metaclass of interest with respect to which this most speci c information is determined We demonstrate that contextual instance inheritance is a powerful conceptual modeling mech anism capable of expressing valuable information about instances We also provide a framework in which derived instance inherited properties can be represented and retrieved in the same way as usual properties