tailieunhanh - Intensional Answers to Database Queries

Some of the actual queries resulting from storing everything and being able to pivot or correlate using various metadata attributes, include: finding the title of a book from an email, invoice, or recipient’s thank you; retrieving web pages for a reference while authoring a paper and commuting on the train; finding a particular tile model that was used in a 5 year old home renovation by retrieving the contractor’s specifications and invoice; recalling a distant colleague by looking at all correspondences about “storage”; replaying a stored phone message for a name or possibly sharing such a message; using a caller. | 444 IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING VOL. 6 NO. 3 JUNE 1994 Intensional Answers to Database Queries Amihai Motro Abstract 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 Intenslonal information the data are referred to as extensional information . Recently 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. In this paper 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. Index Terms Database database extension database intension query cooperative answer extensional answer intenslonal answer I. Introduction WHEN presented with questions the responses of humans often go beyond simple direct answers. For example a person asked a question may prefer to answer a related question or this person may provide additional information that justifies or explains the answer. The emulation of human cooperative behavior in man-machine interfaces has been the subject of many studies in artificial intelligence 25 . Traditionally database systems have been concerned only with providing direct answers to queries with most efforts being aimed at ensuring such properties as correctness efficiency reliability and convenience. In recent years however various research .

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