Botoeva, E, Kontchakov, R, Ryzhikov, V, Wolter, F and Zakharyaschev, M
(2016)
Games for query inseparability of description logic knowledge bases.
Artificial Intelligence, 234.
pp. 78-119.
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Abstract
We consider conjunctive query inseparability of description logic knowledge bases with respect to a given signature - a fundamental problem in knowledge base versioning, module extraction, forgetting and knowledge exchange. We give a uniform game-theoretic characterisation of knowledge base conjunctive query inseparability and develop worst-case optimal decision algorithms for fragments of Horn-ALCHI, including the description logics underpinning OWL 2 QL and OWL 2 EL. We also determine the data and combined complexity of deciding query inseparability. While query inseparability for all of these logics is P-complete for data complexity, the combined complexity ranges from P- to ExpTime- to 2ExpTime-completeness. We use these results to resolve two major open problems for OWL 2 QL by showing that TBox query inseparability and the membership problem for universal conjunctive query solutions in knowledge exchange are both ExpTime-complete for combined complexity. Finally, we introduce a more flexible notion of inseparability which compares answers to conjunctive queries in a given signature over a given set of individuals. In this case, checking query inseparability becomes NP-complete for data complexity, but the ExpTime- and 2ExpTime-completeness combined complexity results are preserved.
Item Type: | Article |
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Uncontrolled Keywords: | Description logic, Knowledge base, Conjunctive query, Query inseparability, Games on graphs, Computational complexity |
Depositing User: | Symplectic Admin |
Date Deposited: | 07 Jul 2016 10:24 |
Last Modified: | 19 Jan 2023 07:36 |
DOI: | 10.1016/j.artint.2016.01.010 |
Related URLs: | |
URI: | https://livrepository.liverpool.ac.uk/id/eprint/3001404 |