Theoretical Investigation of Information Sharing for Semantic and Object-Oriented Databases

这项研究正在开发用于重组和合并来自不同数据库的信息的语言和机制，并正在研究这些语言的理论基础。该研究使用PI正式定义的ILOG语言，这些语言允许对数据库重构进行声明性规范。这些语言的某些技术属性提供了与逻辑编程的紧密联系。该研究还在开发用于数据合并的ILOG扩展；这里的一个中心问题涉及确定两个或多个不同数据库中的对象标识符（oid）何时引用“世界上”相同的对象，并在这种情况下开发适当的机制来“合并”这些oid。正在研究的具体理论问题包括：试图描述两个（重组或合并）计划何时是等效的；探索程序的代数性质（如结合性、分配性）；开发针对重组、合并数据库的查询翻译算法；如果实现了这些数据库，还可以对它们进行增量更新。实验工作将在现实条件下测试算法和视图更新方法。研究结果将为所有涉及数据共享的数据库应用提供一个重要的组成部分。

This research is developing languages and mechanisms for restructuring and merging information from disparate databases, and is studying the theoretical foundations of such languages.The research uses the PI's formally defined ILOG languages, which permit the declarative specification of database restructuring. Certain technical properties of these languagesprovide a strong connection to logic programming. The research is also developing extensions to ILOG for data merging; a central problem here involves determining when object identifiers (OIDs) in two or more distinct databases refer to the same object "in the world", and developing appropriate mechanisms for "merging" the OIDs in this case. Specific theoretical questions under study include: attempting to characterize when two (restructuring or merging) programs are equivalent; exploring algebraic properties of programs (e.g., associativity, distributivity);developing algorithms for the translation of queries against restructured, merged databases; and for incrementally updating such databases if they are materialized. Experimental work will be performed to test the algorithms and view update methodologiesunder realistic conditions. The results obtained by the researchwill provide a crucial component for all database applications which involve data sharing.