Extension of the Deductive Databases Formalism for Supporting Complex Hierarchically Structured Objects

Extension of the deductive databases formalism is presented, which provides support to complex hierarchically structured objects (including object creation). As it is accepted in deductive object-oriented data languages, the objects are represented by the set of facts denoting the object attributes and the links between objects. A new approach for representing the aggregative links in a deductive data language is proposed, in which the hierarchical structure of such links and their physical implementation can be handled adequately. We also introduce two constructs: reference variables and nested rules, which can be used for flexibly expressing and efficiently implementing complex queries, including data restructuring.