Multiple object representations

In the object-oriented paradigm, objects are instances of the conceptual entities that describe their structure and behavior i.e, the classes. Recent applications of object-oriented programming languages and databases in areas like engineering design and genetics have demonstrated the limits of this assumption. Object instances cannot always conform to [heir class definitions. They may evolve during the application lifetime. Further, a class may be only one specific object representation among several others required by the users. This paper relaxes some constraints usually associated with instantiation mechanisms. An object instance is no longer considered as a perfect representative of a specific class. [t ctin bear distortions with its class definition. This is called here tlexible instantiation. An instance can also belong simultaneously to different classes. These classes need not be related by any direct or indirect specialization relationship, “l’his is called here multiple instantiation, II is shown how classifiuauon mechanisms complement adequatly multiple instantiation. The characteristics of such LI clitssitication mechanism are described. It is implemented for tin object-based knowledge representation model called