Computing certain answers in the presence of dependencies

Afrati, FN; Kiourtis, N

dc.contributor.author	Afrati, FN	en
dc.contributor.author	Kiourtis, N	en
dc.date.accessioned	2014-03-01T01:33:03Z
dc.date.available	2014-03-01T01:33:03Z
dc.date.issued	2010	en
dc.identifier.issn	0306-4379	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20288
dc.subject	Certain answers	en
dc.subject	Conjunctive queries	en
dc.subject	Dependencies	en
dc.subject	Query rewritings	en
dc.subject	Views	en
dc.subject.classification	Computer Science, Information Systems	en
dc.subject.other	Certain answers	en
dc.subject.other	Conjunctive queries	en
dc.subject.other	Efficient algorithm	en
dc.subject.other	Local as views	en
dc.subject.other	Query answering	en
dc.subject.other	Query rewritings	en
dc.subject.other	Subgoals	en
dc.subject.other	Algorithms	en
dc.subject.other	Query languages	en
dc.title	Computing certain answers in the presence of dependencies	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.is.2009.08.002	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.is.2009.08.002	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	In this paper we consider conjunctive queries and views, and we investigate the problem of query answering using views in the presence of dependencies and in particular the problem of finding equivalent and maximally contained rewritings of a query using a set of views in the presence of dependencies. We present an efficient sound and complete algorithm CoreCoverC which finds equivalent rewritings with the minimum number of subgoals in the presence of weakly acyclic local as view tuple generating dependencies (C-LAV(W)). We also present an efficient algorithm MINICONC that finds maximally contained rewritings (MCRs) with respect to the language of finite unions of conjunctive queries (UCQ) of a UCQ query Q in the presence of C-LAV(W). We also prove that an IVICR of a UCQ query Q with respect to UCQ computes al the certain answers of Q both in the absence and presence of a set of dependencies C if the chase of Q with C terminates (and, in the case of dependencies, if such an MCR exists). (C) 2009 Elsevier B.V. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Information Systems	en
dc.identifier.doi	10.1016/j.is.2009.08.002	en
dc.identifier.isi	ISI:000273100000003	en
dc.identifier.volume	35	en
dc.identifier.issue	2	en
dc.identifier.spage	149	en
dc.identifier.epage	169	en