2 the Complex Object Model with Identity

This paper presents a rule-based query language for an object-oriented database model. The database model supports complex objects, object identity, classes and types, and a class / type hierarchy. The instances are described by \object relations" which are functions from a set of objects to value sets and other object sets. The rule language is based on object-terms which provide access to objects via the class hierarchy. Rules are divided into two classes: object-preserving rules manipulating existing objects (yielding a new \view" on objects available in the object base) and object-generating rules creating new objects with properties derived from existing objects. The derived object sets are included in a class lattice. We give conditions for whether the instances of the rules' heads are \con-sistent", i.e., represent object relations where the properties of the derived objects are functionally determined by the objects.