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Tractability in probabilistic databases

Dan Suciu
2011 Proceedings of the 14th International Conference on Database Theory - ICDT '11  
Probabilistic database, query evaluation Probabilistic databases are motivated by a large and diverse set of applications that need to query and process uncertain data.  ...  All these applications have large collections of data, where some, or most individual data items are uncertain.  ...  Acknowledgment The author was partially supported by NSF IIS-0713576.  ... 
doi:10.1145/1938551.1938553 dblp:conf/icdt/Suciu11 fatcat:atm4n47iwzh73k7slig5v75taa

Repair checking in inconsistent databases

Foto N. Afrati, Phokion G. Kolaitis
2009 Proceedings of the 12th International Conference on Database Theory - ICDT '09  
Theorem If Σ is the union of a weakly acyclic set of LAV tgds and a set of egds, then the subset-repair checking problem w.r.t. Σ is in PTIME; in fact, it is in LOGSPACE. Proof Idea.  ...  Key property of LAV tgds: only single facts fire a tgd (and no combinations of facts). Hence, LAV tgds are preserved under unions of models.  ...  The consistent answers of q on r w.r.t.  ... 
doi:10.1145/1514894.1514899 dblp:conf/icdt/AfratiK09 fatcat:lvijjkbivnallpzuugigf2w634

Tackling Polytype Queries in Inconsistent Databases: Theory and Algorithm

Dong Xie, Xinbo Chen, Yan Zhu
2012 Journal of Software  
This paper presents several algorithms to tackle a large and practical class of queries, which can obtain the rewritten queries for computing consistent answers.  ...  For a rewritable initial query, a consistent identification statement is constructed based on the join graph by recursive computation; and the statement combines with the initial query to construct a new  ...  The consistent answers for q1 on I are the tuples (Tom) and (Mary). Let q 2 (name, age) = R (name, age). The only consistent answer for q 2 on I is (Mary, 30).  ... 
doi:10.4304/jsw.7.8.1861-1866 fatcat:oleyvdabkvb7xfz2e2avof2are

Tractable vs. Intractable Cases of Query Answering under Matching Dependencies [chapter]

Leopoldo Bertossi, Jaffer Gardezi
2014 Lecture Notes in Computer Science  
Previous work identified classes of queries and sets of MDs for which resolved query answering is tractable, with special emphasis on cyclic sets of MDs.  ...  In those tractable cases, we find conjunctive queries with certain restrictions on joins, and sets of MDs that cyclically depend on each other. These are the (cyclic) HSC sets identified in [14] .  ...  We identify a class of conjunctive queries that are relevant for the investigation of tractability vs. intractability of RQA.  ... 
doi:10.1007/978-3-319-11508-5_5 fatcat:3qvbckykmrcy7iobppyipesipq

On the Complexity of Consistent Query Answering in the Presence of Simple Ontologies

Meghyn Bienvenu
2021 PROCEEDINGS OF THE THIRTIETH AAAI CONFERENCE ON ARTIFICIAL INTELLIGENCE AND THE TWENTY-EIGHTH INNOVATIVE APPLICATIONS OF ARTIFICIAL INTELLIGENCE CONFERENCE  
In order to better understand the source of this intractability, we investigate the complexity of consistent query answering for simple ontologies consisting only of class subsumption and class disjointness  ...  Recent work on consistent query answering in the presence of ontologies has shown this problem to be intractable in data complexity even for ontologies expressed in lightweight description logics.  ...  a given set of integrity constraints (typically, functional dependencies) and a given CQ, whether the associated consistent query answering problem is first-order expressible, tractable, or intractable  ... 
doi:10.1609/aaai.v26i1.8218 fatcat:5eavfcgoorffha4znlxpbpbxry

Small is Again Beautiful in Description Logics

Franz Baader, Carsten Lutz, Anni-Yasmin Turhan
2010 Künstliche Intelligenz  
OWL DL, the standard ontology language for the Semantic Web, is based on such an expressive DL for which reasoning is highly intractable.  ...  This and other reasons have led to the development of two new families of light-weight DLs, EL and DL-Lite, which recently have been proposed as profiles of OWL 2, the new version of the OWL standard.  ...  Given a union of conjunctive queries or a conjunctive query q and a knowledge base K, the set of answers to q over K (denoted ans(q, K)) consists of all tuples a of individual names appearing in the knowledge  ... 
doi:10.1007/s13218-010-0004-8 fatcat:mqdsof4hcnfibgouuai35ibda4

On the Complexity of Query Answering under Matching Dependencies for Entity Resolution [article]

Leopoldo Bertossi, Jaffer Gardezi
2013 arXiv   pre-print
In previous work we identified some tractable cases (i.e. for certain classes of queries and MDs) of resolved query answering.  ...  The resolved answers to queries are those that are invariant under the resulting class of resolved instances.  ...  The idea is to rewrite a query, say conjunctive, into a new query such that the new query on the inconsistent database returns as usual answers the consistent answers to the original query.  ... 
arXiv:1304.7854v2 fatcat:je672nxxv5dizd27ggcmdimzqe

First-order query rewriting for inconsistent databases

Ariel Fuxman, Renée J. Miller
2007 Journal of computer and system sciences (Print)  
In contrast, in this paper we give an algorithm that computes the consistent answers for a large and practical class of conjunctive queries.  ...  In particular, we concentrate on sets of constraints that consist of key dependencies. Most of the existing work has focused on identifying intractable cases of this problem.  ...  We would like to thank Leonid Libkin, Marcelo Arenas, Pablo Barcelo, and Ken Pu for their comments and feedback.  ... 
doi:10.1016/j.jcss.2006.10.013 fatcat:ecyabmao4ncctot7e4qodwy52a

First-Order Query Rewriting for Inconsistent Databases [chapter]

Ariel D. Fuxman, Renée J. Miller
2004 Lecture Notes in Computer Science  
In contrast, in this paper we give an algorithm that computes the consistent answers for a large and practical class of conjunctive queries.  ...  In particular, we concentrate on sets of constraints that consist of key dependencies. Most of the existing work has focused on identifying intractable cases of this problem.  ...  We would like to thank Leonid Libkin, Marcelo Arenas, Pablo Barcelo, and Ken Pu for their comments and feedback.  ... 
doi:10.1007/978-3-540-30570-5_23 fatcat:snnu2sghyzavxbji2pgovypjye

Enumeration in Data Management (Dagstuhl Seminar 19211)

Endre Boros, Benny Kimelfeld, Reinhard Pichler, Nicole Schweikardt, Michael Wagner
2019 Dagstuhl Reports  
Towards the objectives, the seminar included tutorials on the topic, invited talks, presentations of open problems, working groups on the open problems, discussions on platforms to compile the community  ...  knowledge, and the construction of various skeletons of such compilations.  ...  We show that some non-redundant unions containing intractable CQs are tractable. Interestingly, some unions consisting of only intractable CQs are tractable too.  ... 
doi:10.4230/dagrep.9.5.89 dblp:journals/dagstuhl-reports/BorosKPS19 fatcat:gfir76niqfhmno2hpj563cwwqe

Query languages for data exchange

Marcelo Arenas, Pablo Barceló, Juan Reutter
2009 Proceedings of the 12th International Conference on Database Theory - ICDT '09  
In particular, we show that the certain answers to a DATALOG C( =) program can be computed in polynomial time (in terms of data complexity), and that every union of conjunctive queries with at most one  ...  This syntactic restriction is given by two conditions that are optimal, in the sense that computing certain answers becomes intractable if one removes any of them.  ...  The authors were supported by: Arenas and Reutter -FONDECYT grant 1070732; Barceló -FONDECYT grant 11080011; Arenas and Barceló -grant P04-067-F from the Millennium Nucleus Centre for Web Research.  ... 
doi:10.1145/1514894.1514904 dblp:conf/icdt/ArenasBR09 fatcat:lvnmfo35xngwzn5a4xrcxr6sve

Query Languages for Data Exchange: Beyond Unions of Conjunctive Queries

Marcelo Arenas, Pablo Barceló, Juan Reutter
2010 Theory of Computing Systems  
In particular, we show that the certain answers to a DATALOG C( =) program can be computed in polynomial time (in terms of data complexity), and that every union of conjunctive queries with at most one  ...  This syntactic restriction is given by two conditions that are optimal, in the sense that computing certain answers becomes intractable if one removes any of them.  ...  The authors were supported by: Arenas and Reutter -FONDECYT grant 1070732; Barceló -FONDECYT grant 11080011; Arenas and Barceló -grant P04-067-F from the Millennium Nucleus Centre for Web Research.  ... 
doi:10.1007/s00224-010-9259-6 fatcat:vhf7p6m2h5gcbbgw5drytzarzi

XML data exchange

Marcelo Arenas, Leonid Libkin
2005 Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems - PODS '05  
We then move to query answering, and prove a dichotomy theorem that classifies data exchange settings into those over which query answering is tractable, and those over which it is coNP-complete, depending  ...  In this paper, we start looking into the basic properties of XML data exchange, that is, restructuring of XML documents that conform to a source DTD under a target DTD, and answering queries written over  ...  comments on the draft.  ... 
doi:10.1145/1065167.1065171 dblp:conf/pods/ArenasL05 fatcat:7sbvhte7mnapxnp4w7uwdopz5e

On the efficiency of checking perfect privacy

Ashwin Machanavajjhala, Johannes Gehrke
2006 Proceedings of the twenty-fifth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems - PODS '06  
One very attractive notion of privacy is perfect privacy -a secret is expressed through a query QS, and a query QV is answered only if it discloses no information about the secret query QS.  ...  In this paper, we show that for large interesting subclasses of conjunctive queries enforcing perfect privacy is tractable.  ...  Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the sponsors.  ... 
doi:10.1145/1142351.1142375 dblp:conf/pods/MachanavajjhalaG06 fatcat:fbr6hv5cufcnlc222vgoxk4wjq

Tractable Cases of Clean Query Answering under Entity Resolution via Matching Dependencies [chapter]

Jaffer Gardezi, Leopoldo Bertossi
2012 Lecture Notes in Computer Science  
The clean answers to queries (which we call the resolved answers) are invariant under the resulting class of instances.  ...  This is an important result, because it leads to tractable cases of resolved query answering. Further tractable cases are derived by making connections with tractable cases of CQA.  ...  The latter paper introduced the framework used in this paper, and proved that the resolved answer problem is intractable in some cases.  ... 
doi:10.1007/978-3-642-33362-0_14 fatcat:b2f35idgp5c4lbesgmzbvrzkmm
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