Representing generalizations and exceptions in expert database systems

摘要

To further increase the decision support capabilities of database management systems, previous research has suggested the development of expert database systems by coupling expert systems to database management systems. One approach is to combine the capabilities of logic systems and relational databases. Logic allows the specification of general rules representing abstract knowledge while database management systems provide efficient management of large masses of data representing specific facts. In many practical situations, general rules cannot or are not intended to describe every possible case, thus leading to the necessity of representing exceptions. A classification of exceptions is made in this paper, and their representation in expert database systems that combine logic and relational databases is discussed. In addition, a description is made of extensions needed to the relational language SQL to permit the specification of rules that allow exceptions.