making object-oriented schemas more expressive
Current object-oriented data models lack several important features that would allow one to express relevant knowledge about the classes of schema. In particular, there is no data model supporting simultaneously the inverse of the functions represented by attributes, the union, the intersection and the complement of classes, the possibility of using nonbinary relations, and the possibility of expressing cardinality constraints on attributes and relations. In this paper we define a new data model, called CAR , which extends the basic core of current object-oriented data models with all the above mentioned features. A technique is then presented both for checking the consistency of class definitions, and for computing the logical sequences of the knowledge represented in the schema. Finally, the inherent complexity of reasoning in CAR is investigated, and the complexity of our inferencing technique is studied, depending on various assumptions on the schema.
object-oriented schema express data models feature relevance knowledge class attributes intersection constraint paper core consistency definition computation sequence complexity reasoning