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      To Form a More Perfect Union (Intersection, Difference)

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      Proceedings of the Fifth International Workshop on Database Programming Languages (DBPL-5)

      Database Programming Languages

      6-8 September 1995

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            Abstract

            The AQUA [16] query algebra allows user-defined equivalence relations as arguments to query operators that generalize standard set operations. These predicates determine what objects are included in the query result, and the duplicates that must be removed. While an expressive enhancement, the use of arbitrary equivalence relations to decide set membership can result in sets with counterintuitive behavior, and therefore can make queries return unreasonable results. In this paper, we show that equality predicates assume two roles with respect to sets. Distinguishers differentiate between set members and implicitly give meaning to standard set properties such as set equality. Constructors determine which object from input sets contribute to the query result. The requirements of distinguishers and constructors differ. AQUA’s set operators are problematic because they use constructors where distinguishers are required. We propose alternatives to AQUA’s set operators that address this limitation.

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            Author and article information

            Contributors
            Conference
            September 1995
            September 1995
            : 1-12
            Affiliations
            [0001]Brown University

            Providence, RI, USA
            Article
            10.14236/ewic/DBPL1995.5
            0322cad2-935e-4244-9c2d-e8756efff2f4
            © Mitch Cherniack et al. Published by BCS Learning and Development Ltd. Proceedings of the Fifth International Workshop on Database Programming Languages, Gubbio, Umbria, Italy

            This work is licensed under a Creative Commons Attribution 4.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

            Proceedings of the Fifth International Workshop on Database Programming Languages
            DBPL-5
            5
            Gubbio, Umbria, Italy
            6-8 September 1995
            Electronic Workshops in Computing (eWiC)
            Database Programming Languages
            Product
            Product Information: 1477-9358BCS Learning & Development
            Self URI (journal page): https://ewic.bcs.org/
            Categories
            Electronic Workshops in Computing

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