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http://hdl.handle.net/1942/29111
Title: | A monotone preservation result for Boolean queries expressed as a containment of conjunctive queries | Authors: | SURINX, Dimitri VAN DEN BUSSCHE, Jan |
Issue Date: | 2019 | Publisher: | ELSEVIER | Source: | INFORMATION PROCESSING LETTERS, 150, p. 1-5 | Abstract: | When a relational database is queried, the result is normally a relation. Some queries, however, only require a yes/no answer; such queries are often called boolean queries. It is customary in database theory to express boolean queries by testing nonemptiness of query expressions. Another interesting way for expressing boolean queries are containment statements of the form Q(1) subset of Q(2) where Q(1) and Q(2) are query expressions. Here, for any input instance I, the boolean query result is true if Q(1) (I) is a subset of Q(2) (I) and false otherwise. In the present paper we will focus on nonemptiness and containment statements about conjunctive queries. The main goal is to investigate the monotone fragment of the containments of conjunctive queries. In particular, we show a preservation like result for this monotone fragment. That is, we show that, in expressive power, the monotone containments of conjunctive queries are exactly equal to conjunctive queries under nonemptiness. (C) 2019 Elsevier B.V. All rights reserved. | Notes: | [Surinx, Dimitri; Van den Bussche, Jan] Hasselt Univ, Martelarenlaan 42, B-3500 Hasselt, Belgium. | Keywords: | Databases; Query languages; Expressive power;Databases; Query languages; Expressive power | Document URI: | http://hdl.handle.net/1942/29111 | ISSN: | 0020-0190 | e-ISSN: | 1872-6119 | DOI: | 10.1016/j.ipl.2019.06.001 | ISI #: | 000480666800001 | Rights: | 2019 Elsevier B.V. All rights reserved. | Category: | A1 | Type: | Journal Contribution | Validations: | ecoom 2020 |
Appears in Collections: | Research publications |
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surinx 1.pdf Restricted Access | Published version | 249.02 kB | Adobe PDF | View/Open Request a copy |
cqpreserv.pdf | Peer-reviewed author version | 237.12 kB | Adobe PDF | View/Open |
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