Preserving and generating objects in the LIVING IN A LATTICE rule language

LIVING IN A LATTICE is presented as a rule-based query language for an object-oriented database model. The model supports complex objects, object identity, and is-a-relationships. 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 an access to objects via is-a-relationships. Rules are divided into two classes: object-preserving rules manipulating existing objects and object-generating ones creating objects with properties derived from existing objects. The derived object sets are included in a lattice of object types. Some conditions are given under which the instances of the rule's heads are consistent, i.e., where the properties of the derived objects are functionally determined by the objects.<
>