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    Query inseparability for ALC ontologies

    Botoeva, E. and Lutz, C. and Ryzhikov, Vladislav and Wolter, F. and Zakharyaschev, Michael (2019) Query inseparability for ALC ontologies. Artificial Intelligence 272 , pp. 1-51. ISSN 0004-3702.

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    Abstract

    We investigate the problem whether two ALC ontologies are indistinguishable (or inseparable) by means of queries in a given signature, which is fundamental for ontology engineering tasks such as ontology versioning, modularisation, update, and forgetting. We consider both knowledge base (KB) and TBox inseparability. For KBs, we give model-theoretic criteria in terms of (finite partial) homomorphisms and products and prove that this problem is undecidable for conjunctive queries (CQs), but 2ExpTime-complete for unions of CQs (UCQs). The same results hold if (U)CQs are replaced by rooted (U)CQs, where every variable is connected to an answer variable. We also show that inseparability by CQs is still undecidable if one KB is given in the lightweight DL EL and if no restrictions are imposed on the signature of the CQs. We also consider the problem whether two ALC TBoxes give the same answers to any query over any ABox in a given signature and show that, for CQs, this problem is undecidable, too. We then develop model-theoretic criteria for HornALC TBoxes and show using tree automata that, in contrast, inseparability becomes decidable and 2ExpTime-complete, even ExpTime-complete when restricted to (unions of) rooted CQs.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): Description logicKnowledge base, Conjunctive query, Query inseparability, Computational complexity, Tree automaton
    School: Birkbeck Schools and Departments > School of Business, Economics & Informatics > Computer Science and Information Systems
    Depositing User: Dr Vladislav Ryzhikov
    Date Deposited: 15 Oct 2018 14:44
    Last Modified: 28 Jul 2019 03:15
    URI: http://eprints.bbk.ac.uk/id/eprint/24607

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