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Intensional Answers to Database Queries
June 1994 (vol. 6 no. 3)
pp. 444-454

In addition to data, database systems store various kinds of information about their data. Examples are: class hierarchies, to define the various data classes and their relationships; integrity constraints, to state required relationships among the data; and inference rules, to define new classes in terms of known classes. This information is often referred to as intensional information (the data are referred to as extensional information). There have been several independent research works that suggested ways by which intensional information may be used to improve the conventional (extensional) database answers. Although each of these efforts developed its own specific methods, they all share a common belief: database answers would be improved if accompanied by intensional statements that describe them more abstractly. We study and compare the various approaches to intensional answers by using various classifications; we examine their relative merits with regard to key aspects; we discuss remaining issues; and we offer new research directions.

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Index Terms:
query processing; database management systems; data integrity; user interfaces; database queries; intensional information; database systems; class hierarchies; data classes; integrity constraints; inference rules; extensional information; database answers; intensional statements; classifications; research directions; user interfaces
A. Motro, "Intensional Answers to Database Queries," IEEE Transactions on Knowledge and Data Engineering, vol. 6, no. 3, pp. 444-454, June 1994, doi:10.1109/69.334858
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