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On Equivalence and Cores for Incomplete Databases in Open and Closed Worlds [article]

Henrik Forssell and Evgeny Kharlamov and Evgenij Thorstensen
2020 arXiv   pre-print
Several semantics for such instances have been proposed and include open (OWA), closed (CWA), and open-closed (OCWA) world.  ...  Data exchange heavily relies on the notion of incomplete database instances.  ...  Acknowledgement: This work was partially supported by the SIRIUS Centre, Norwegian Research Council project number 237898 and project number 230525.  ... 
arXiv:2001.04757v1 fatcat:7hsehmmkp5e77mwbasahozxvb4

On Equivalence and Cores for Incomplete Databases in Open and Closed Worlds

Henrik Forssell, Evgeny Kharlamov, Evgenij Thorstensen, Jean Christoph Jung, Carsten Lutz
2020 International Conference on Database Theory  
Several semantics for such instances have been proposed and include open (OWA), closed (CWA), and open-closed (OCWA) world.  ...  Data exchange heavily relies on the notion of incomplete database instances.  ...  On Equivalence and Cores for Incomplete DBs in Open and Closed Worlds 2.3.1 Open World Approach: OWA Under OWA (Open World Assumption) an instance A represents the set of complete instances to which A  ... 
doi:10.4230/lipics.icdt.2020.10 dblp:conf/icdt/ForssellKT20 fatcat:kihmi4bsgndqhliqwy7t6n65pu

Towards Characterising Data Exchange Solutions in Open and Closed Words (Extended Abstract)

Henrik Forssell, Evgeny Kharlamov, Evgenij Thorstensen
2017 Alberto Mendelzon Workshop on Foundations of Data Management  
Acknowledgements This was was partially supported by: the Norwegian Research Council grant no. 230525; SIRIUS SFI 1 ; the EPSRC projects MaSI 3 , DBOnto, and ED 3 .  ...  by Libkin et al [12] to a semantics of mixed open-and-closed (OCWA) worlds and they both are based on a different notion of Rep, called Rep A defined for annotated incomplete instances.  ...  Fagin et al [5, 6] proposed an open world (OWA) semantics based on the classical Rep of [8] , which we denote Rep O , Hernich et al [7] proposed a closed world (CWA) semantics, which was further extended  ... 
dblp:conf/amw/ForssellKT17 fatcat:moluqz5monde7gainruqgumwaa

When is naive evaluation possible?

Amélie Gheerbrant, Leonid Libkin, Cristina Sirangelo
2013 Proceedings of the 32nd symposium on Principles of database systems - PODS '13  
For relational databases it is well known that unions of conjunctive queries possess this desirable property, and results on preservation of formulae under homomorphisms tell us that within relational  ...  calculus, this class cannot be extended under the open-world assumption.  ...  Acknowledgments Work partly supported by EPSRC grants G049165 and J015377.  ... 
doi:10.1145/2463664.2463674 dblp:conf/pods/GheerbrantLS13 fatcat:2xzu3dj4xzbpvjvoefjtxvxqd4

Guest editorial: Special issue on database theory

Marcelo Arenas
2011 Journal of computer and system sciences (Print)  
In the article "Data exchange and schema mappings in open and closed worlds", Libkin and Sirangelo propose a mixed semantics for data exchange systems, where some attributes of target schemas are designated  ...  constraints under open-world assumption, that is, under the assumption that the facts stored in the database are only an incomplete specification of the data.  ... 
doi:10.1016/j.jcss.2010.04.004 fatcat:stayokd5gbadtin4ry6g3pmy24

Explainable Certain Answers

Giovanni Amendola, Leonid Libkin
2018 Proceedings of the Twenty-Seventh International Joint Conference on Artificial Intelligence  
We present a general framework for reasoning about them, and show that for open and closed world relational databases, they are precisely the common intersection-based notions of certainty.  ...  For the former, we show that such answers may not exist, or be very large, even in simple cases of querying incomplete data.  ...  The second author is supported by EPSRC grants M025268 and N023056. We are grateful to anonymous referees for their comments.  ... 
doi:10.24963/ijcai.2018/233 dblp:conf/ijcai/AmendolaL18 fatcat:p36xoaalrbgjrilmhllspb3bqq

Naïve Evaluation of Queries over Incomplete Databases

Amélie Gheerbrant, Leonid Libkin, Cristina Sirangelo
2014 ACM Transactions on Database Systems  
from open-world.  ...  Even more, we introduce a general relation-based framework for defining semantics of incompleteness, show how it can be used to capture many known semantics and to introduce new ones, and describe classes  ...  Work partly supported by EP-SRC grants G049165 and J015377. ELECTRONIC APPENDIX The electronic appendix for this article can be accessed in the ACM Digital Library.  ... 
doi:10.1145/2691190.2691194 fatcat:dcgubpmfybfq5apoivdh7esz7u

Incomplete information and certain answers in general data models

Leonid Libkin
2011 Proceedings of the 30th symposium on Principles of database systems of data - PODS '11  
The approach is based on representing degrees of incompleteness via semantics-based orderings on database objects.  ...  open questions on the existence of certain answers in the XML setting; and show that previously studied ordering-based approaches were only adequate for SQL's primitive view of nulls.  ...  Acknowledgments I thank Pablo Barceló, Claire David, Egor Kostylev, and Filip Murlak for helpful discussions on incompleteness and certain answers.  ... 
doi:10.1145/1989284.1989294 dblp:conf/pods/Libkin11 fatcat:vy5kmbdckjepvlbfzbocvsc6em

Closed world chasing

Gösta Grahne, Adrian Onet
2011 Proceedings of the 4th International Workshop on Logic in Databases - LID '11  
We give a new closed world semantics for data exchange called constructible solutions semantics, and argue that this semantics is well suited for answering non-monotonic queries in data exchange.  ...  Note that S ol(I, Σ) is closed under supersets and homomorphic images, and thus encompasses an open world assumption.  ...  An incomplete database is conceptually a set I of complete instances, or possible worlds I. Given a query Q and an incomplete database I, the result of Q on I is Q(I) = {Q(I) ∶ I ∈ I}.  ... 
doi:10.1145/1966357.1966360 dblp:conf/lid/GrahneO11 fatcat:ejdkmgitwjdl3lc4h56xyywdre

Representation systems for data exchange

Gösta Grahne, Adrian Onet
2012 Proceedings of the 15th International Conference on Database Theory - ICDT '12  
Reasoning is modulo homomorphic equivalence (CQ-equivalence), and only unions of conjunctive queries and monotone data exchange mappings are supported.  ...  These systems are based on conditional tables, and they support first order queries and non-monotonic data exchange mappings specified by a large class of second order dependencies.  ...  Acknowledgements We are grateful to the anonymous referees for detailed and constructive comments.  ... 
doi:10.1145/2274576.2274599 dblp:conf/icdt/GrahneO12 fatcat:2pfqeutborc55b5a7fmuspb5hu

Rewritability Results for OMQs with Closed Predicates

Magdalena Ortiz
2020 International Workshop on Description Logics  
The semantics of Description Logic (DL) ontologies adopts the open-world assumption (OWA) from classical first-order logic (FOL), which makes them well suited to reason about incomplete knowledge.  ...  We recall here a small selection of recent results on rewritability of OMQs with closed predicates: two polynomial rewritings into extensions of Datalog for restricted classes of conjunctive queries mediated  ...  Acknowledgments The works reported here were supported by the Austrian Science Fund (FWF) projects P30360, P30873 and W1255.  ... 
dblp:conf/dlog/Ortiz20 fatcat:uf5e25bsabgkfcjykoqs74hobm

CLASSIC: a structural data model for objects

Alexander Borgida, Ronald J. Brachman, Deborah L. McGuinness, Lori Alperin Resnick
1989 SIGMOD record  
One of the strengths of the approach is that the same language plays multiple roles in the processes of de ning and populating the DB, as well as querying and answering. classic for which w e h a ve a  ...  The kind of language of descriptions and queries presented here provides a new arena for the search for languages that are more expressive than conventional DBMS languages, but for which query processing  ...  , and every primitive concept as a unary relation, and one has an ordinary relational database modulo the closed world assumption.  ... 
doi:10.1145/66926.66932 fatcat:j4epfkch3ndqxgjaruy5f5vg5y

CLASSIC: a structural data model for objects

Alexander Borgida, Ronald J. Brachman, Deborah L. McGuinness, Lori Alperin Resnick
1989 Proceedings of the 1989 ACM SIGMOD international conference on Management of data - SIGMOD '89  
One of the strengths of the approach is that the same language plays multiple roles in the processes of de ning and populating the DB, as well as querying and answering. classic for which w e h a ve a  ...  The kind of language of descriptions and queries presented here provides a new arena for the search for languages that are more expressive than conventional DBMS languages, but for which query processing  ...  , and every primitive concept as a unary relation, and one has an ordinary relational database modulo the closed world assumption.  ... 
doi:10.1145/67544.66932 dblp:conf/sigmod/BorgidaBMR89 fatcat:psto7qbwhjbmjmh3c7wv62avay

Completeness of queries over incomplete databases

Simon Razniewski, Werner Nutt
2011 Proceedings of the VLDB Endowment  
I am thankful to Dmitrij Miliaev who has written a Bachelor thesis on the topic of incompleteness and who helped me much to get into the topic.  ...  Without him, his patience and his advice this thesis would not have been possible at all.  ...  Answering queries in such scenarios requires both open-and closed-world reasoning.  ... 
doi:10.14778/3402707.3402715 fatcat:goo2hhz4eja6tjfggfz46hkhdy

Answering aggregate queries in data exchange

Foto Afrati, Phokion G. Kolaitis
2008 Proceedings of the twenty-seventh ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems - PODS '08  
Data exchange is a context in which incomplete information arises, hence one has to cope with a set of possible worlds, instead of a single database.  ...  Our analysis also reveals that, to have meaningful semantics for aggregation in data exchange, a strict closed world assumption has to be adopted in selecting the set of possible worlds.  ...  Data exchange is a framework in which incomplete information arises, hence one has to cope with a set of possible worlds, instead of a single database.  ... 
doi:10.1145/1376916.1376936 dblp:conf/pods/AfratiK08 fatcat:3wltwjmdtvavnieuyoqap2wgqm
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