具有面向对象特征的知识库系统

A KNOWLEDGE BASE SYSTEM WITH OBJECT-ORIENTED FEATURES

本文讨论了具有面向对象特征的知识库系统KBASE^+的数据模型、语言及实现。KBASE^+的数据模型可以方便地支持对象标识、类层次、多继承等面向对象概念。描述性查询语言KBL是DATALOG针对于非一范式关系模型的扩充。本文重构了KBL的语义理论框架,提出了通过计算相关类的下确界来解决属性继承中的冲突问题,通过在KBL程序中添加规则来实现实例继承的方案,本文说明了KBL程序可以转换成语义等价的DATALOG程序,描述了这种转换的基本思想,探索了知识库和面向对象数据库有机结合的可行途径。

KBASE+ is a knowledge-base system with object-oriented features. The data model, query language, and implementation of KBASE+ are presented in this paper. Some object-orientation concepts such as object identity, class hierachy, and multi-inheritance can be supported conveniently by KBASE+ data model. The declarative query language KBL is an extended Datalog, which is adaptable to non-first normal form relation model. The semantic framework of KBL is reconstructed in this paper. The multi-inheritance problem is solved by calculating the greatest lower bound of relevant classes, and the instance inheritance can be achieved through adding some rules. It is shown that KBL program can be transformed to a semantically equivalent Datalog program.