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    Tractable query answering over conceptual schemata (extended abstract)

    Calì, Andrea and Gottlob, G. and Pieris, A. (2010) Tractable query answering over conceptual schemata (extended abstract). In: Bergamaschi, S. and Lodi, S. and Martoglia, R. and Sartori, C. (eds.) Proceedings of the Eighteenth Italian Symposium on Advanced Database Systems, SEBD 2008, 22-25 June 2008, Mondello, PA, Italy. Bologna, Italy: Esculapio Editore, pp. 454-461. ISBN 9788874883691.

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    We address the problem of answering conjunctive queries over ex- tended Entity-Relationship (EER) schemata with is-a among entities and relation- ships, and cardinality constraints. This is a common setting in conceptual da ta modeling, where reasoning over incomplete data with respect to a knowled ge base is required. We adopt a semantics for EER schemata based on their rela- tional representation. We identify a wide class of EER schemata for which q uery answering is tractable in data complexity; the crucial condition for tractability is the separability between maximum-cardinality constraints (represented as key constraints in relational form) and the other constraints. We provide, by m eans of a graph-based representation, a necessary and sufficient syntactic condition for separability, thus precisely identifying the class of separable schemata. N egative constraints can be added to the EER formalism, while still keeping query ans wer- ing tractable. Our formalism is general enough to properly generalize the most widely adopted knowledge representation languages.


    Item Type: Book Section
    School: Birkbeck Faculties and Schools > Faculty of Science > School of Computing and Mathematical Sciences
    Research Centres and Institutes: Birkbeck Knowledge Lab
    Depositing User: Administrator
    Date Deposited: 27 Jan 2014 12:14
    Last Modified: 09 Aug 2023 12:33


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