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    Query answering under expressive entity-relationship schemata

    Calì, Andrea and Gottlob, G. and Pieris, A. (2010) Query answering under expressive entity-relationship schemata. In: Parsons, J. and Woo, C. and Saeki, M. and Shoval, P. and Wand, Y. (eds.) Conceptual Modeling. Lecture Notes in Computer Science 6412 6412. London, UK: Springer, pp. 347-361. ISBN 9783642163739.

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    We address the problem of answering conjunctive queries under constraints representing schemata expressed in an extended version of the Entity- Relationship model. This extended model, called ER +  model, comprises is-a constraints among entities and relationships, plus functional and mandatory participation constraints. In particular, it allows arbitrary permutations of the roles in is-a among relationships. A key notion that ensures high tractability in ER +  schemata is separability, i.e., the absence of interaction between the functional participation constraints and the other constructs of ER + .We provide a precise syntactic characterization of separable ER +  schemata, called ER± schemata, by means of a necessary and sufficient condition. We present a complete complexity analysis of the conjunctive query answering problem under ER± schemata. We show that the addition of so-called negative constraints does not increase the complexity of query answering. With such constraints, our model properly generalizes the most widely-adopted tractable ontology 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: Sarah Hall
    Date Deposited: 10 May 2013 08:46
    Last Modified: 09 Aug 2023 12:33


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