Repair checking in inconsistent databases: Algorithms and complexity

Afratit, FN; Kolaitis, PG

dc.contributor.author	Afratit, FN	en
dc.contributor.author	Kolaitis, PG	en
dc.date.accessioned	2014-03-01T02:46:30Z
dc.date.available	2014-03-01T02:46:30Z
dc.date.issued	2009	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/32678
dc.subject	CoNP-complete problem	en
dc.subject	Consistent query answering	en
dc.subject	Database repairs	en
dc.subject	Equality-generating dependencies	en
dc.subject	Inconsistent databases	en
dc.subject	Polynomial time	en
dc.subject	Repair checking	en
dc.subject	Tuple-generating dependencies	en
dc.subject	Weakly acyclic set	en
dc.subject.other	CoNP-complete problem	en
dc.subject.other	Consistent query answering	en
dc.subject.other	Database repairs	en
dc.subject.other	Equality-generating dependencies	en
dc.subject.other	Inconsistent databases	en
dc.subject.other	Polynomial time	en
dc.subject.other	Tuple-generating dependencies	en
dc.subject.other	Weakly acyclic set	en
dc.subject.other	Algorithms	en
dc.subject.other	Database systems	en
dc.subject.other	Polynomial approximation	en
dc.subject.other	Quality assurance	en
dc.subject.other	Set theory	en
dc.subject.other	Repair	en
dc.title	Repair checking in inconsistent databases: Algorithms and complexity	en
heal.type	conferenceItem	en
heal.identifier.primary	10.1145/1514894.1514899	en
heal.identifier.secondary	http://dx.doi.org/10.1145/1514894.1514899	en
heal.publicationDate	2009	en
heal.abstract	Managing inconsistency in databases has long been recognized as an important problem. One of the most promising approaches to coping with inconsistency in databases is the framework of database repairs, which has been the topic of an extensive investigation over the past several years. Intuitively, a repair of an inconsistent database is a consistent database that differs from the given inconsistent database in a minimal way. So far, most of the work in this area has addressed the problem of obtaining the consistent answers to a query posed on an inconsistent database. Repair checking is the following decision problem: given two databases r and r′, is r′ a repair of r? Although repair checking is a fundamental algorithmic problem about inconsistent databases, it has not received as much attention as consistent query answering. In this paper, we give a polynomial-time algorithm for subset-repair checking under integrity constraints that are the union of a weakly acyclic set of local-as-view (LAV) tuple-generating dependencies and a set of equality-generating dependencies. This result significantly generalizes earlier work for subset-repair checking when the integrity constraints are the union of an acyclic set of inclusion dependencies and a set of functional dependencies. We also give a polynomial-time algorithm for symmetric-difference repair checking, when the integrity constraints form a weakly acyclic set of LAV tgds. After this, we establish a number of complexity-theoretic results that delineate the boundary between tractability and intractability for the repair-checking problem. Specifically, we show that the aforementioned tractability results are optimal; in particular, subset-repair checking for arbitrary weakly acyclic sets of tuple-generating dependencies is a coNP-complete problem. We also study cardinality-based repairs and show that cardinality-repair checking is coNP-complete for various classes of integrity constraints encountered in database design and data exchange. Copyright 2009 ACM.	en
heal.journalName	ACM International Conference Proceeding Series	en
dc.identifier.doi	10.1145/1514894.1514899	en
dc.identifier.volume	361	en
dc.identifier.spage	31	en
dc.identifier.epage	41	en