{"type":"ScholarlyArticle","title":"Tractable Queries for Lightweight Description Logics","authors":[{"name":"Meghyn Bienvenu","slug":"meghyn-bienvenu","given":"Meghyn","family":"Bienvenu","affiliation":""},{"name":"Magdalena Ortiz","slug":"magdalena-ortiz","given":"Magdalena","family":"Ortiz","affiliation":""},{"name":"Mantas Simkus","slug":"mantas-simkus","given":"Mantas","family":"Simkus","affiliation":""},{"name":"Guohui Xiao","slug":"guohui-xiao","given":"Guohui","family":"Xiao","affiliation":""}],"abstract":"It is a classic result in database theory that conjunctive query (CQ) answering, which is NP-complete in general, is feasible in polynomial time when restricted to acyclic queries. Subsequent results identified more general structural properties of CQs (like bounded treewidth) which ensure tractable query evaluation. In this paper, we lift these tractability results to knowledge bases formulated in the lightweight description logics DL-Lite and ELH. The proof exploits known properties of query matches in these logics and involves a query-dependent modification of the data. To obtain a more practical approach, we propose a concrete polynomial-time algorithm for answering acyclic CQs based on rewriting queries into datalog programs. A preliminary evaluation suggests the interest of our approach for handling large acyclic CQs.","doi":null,"url":"https://ijcai.org/proceedings/2013/120","pdf":"https://ijcai.org/proceedings/2013/0120.pdf","markdown":"https://ijcai.org/proceedings/2013/120.md","bibtex":"https://ijcai.org/proceedings/2013/bibtex/120","volume":{"slug":"2013","title":"Proceedings of the Twenty-Third International Joint Conference on Artificial Intelligence","short_title":"IJCAI 2013","url":"https://ijcai.org/proceedings/2013/","year":2013,"location":"Beijing, China","dates":"3–9 August 2013","editors":"Francesca Rossi","isbn":"978-1-57735-633-2","publisher":"AAAI Press / International Joint Conferences on Artificial Intelligence","doi_prefix":""},"section":null,"track":"","number":120,"pages":{"first":768,"last":773},"keywords":[],"videos":[],"references":[],"license_note":"Copyright International Joint Conferences on Artificial Intelligence."}