Object-Oriented Knowledge Base Management Systems

在过去，我们提出了一个知识库框架，称为面向对象知识库（OOKB），它成功地将演绎数据库、面向对象编程和逻辑编程的概念结合在一起。在本研究中，我们提出将面向对象的知识库框架扩展为一个高效的知识库管理系统。知识管理：在我们的研究中，我们提出了必要的结构来描述我们关于系统级对象的知识（元知识），如完整性约束、演绎定律、类、方法和事务。我们还建议在知识频繁更新的动态环境中使用元级知识，以确保知识的质量，并便于知识库的控制。查询处理/优化：在查询处理的背景下，我们提出了一种程序转换方法来避免穷举搜索。转换系统使用重写规则将查询的部分替换为一些语义上等价的子查询，这些子查询可以更有效地解决问题。随后，转换后的查询中的连词被动态地重新排序，以最小化求值成本。并发控制：结合(a)中提出的元知识结构，我们提出并发控制（在对知识和数据的并发操作之间）可以是面向对象的，这样它就可以根据对象的语义进行定制。同时，我们将可能发生的冲突分为六类，并提出并发控制应该在知识层和对象层进行。

In the past, we have proposed a knowledge base framework called Object-Oriented Knowledge Base (OOKB) which successfully combines the concepts of deductive database, object-oreiented programming and logic programming. In this research, we propose to extend the framework of object-oriented knowledge base with an efficient knowledge base management system. In particular, we propose the following research tasks: Knowledge Management: In our research, we propose the necessary constructs to describe our knowledge (meta-knowledge) about the system-level objects such as integrity constraints, deductive laws, classes, methods, and transactions. We also propose to employ the meta-level knowledge to ensure the quality of knowledge in a dynamic environment where knowledge is updated frequently and to facilitate to control of knowledge bases. Query Processing/Optimization: In the context of query processing, we propose a program transformation approach to avoid exhaustive search. The transformation system employs rewriting rules to substitute pieces of a query with some semantically equivalent sub-queries that can be solved more efficiently. Subsequently, the conjuncts in the transformed query are reorderd dynamically to minimize the evaluation cost. Concurreny Control: Coupled with the meta-knowledge constructs proposed in (a), we propose that concurrency control (among concurrent operations to knowledge as well as data) can be object-oreiented such that it can be customized according to the semantics of objects. Also, we classify the possible conflicts into six categoried and propose that concurrency control should be performed at knowledge level as well as object level.