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Answering SPARQL Queries over Databases under OWL 2 QL Entailment Regime [chapter]

Roman Kontchakov, Martin Rezk, Mariano Rodríguez-Muro, Guohui Xiao, Michael Zakharyaschev
2014 Lecture Notes in Computer Science  
We present an extension of the ontology-based data access platform Ontop that supports answering SPARQL queries under the OWL 2 QL direct semantics entailment regime for data instances stored in relational  ...  OWL 2 QL graph patterns are constructed from OWL 2 QL BGPs using the SPARQL operators. Finally, an OWL 2 QL query is a pair (P, V ), where P is an OWL 2 QL graph pattern and V ⊆ var(P ).  ...  SPARQL queries under the OWL 2 QL entailment regime with data instances stored in a database.  ... 
doi:10.1007/978-3-319-11964-9_35 fatcat:qxyznp6o3baldm7flrw4gjouki

Towards Reconciling SPARQL and Certain Answers (Extended Abstract)

Shqiponja Ahmetaj, Wolfgang Fischl, Reinhard Pichler, Mantas Simkus, Sebastian Skritek
2015 Alberto Mendelzon Workshop on Foundations of Data Management  
by the presence of OWL 2 QL entailment under the proposed semantics.  ...  However, the semantics of query answering under SPARQL entailment regimes is defined in a more naive and much less expressive way than the certain answer semantics usually adopted in database and DL literature  ...  In [2] , the authors describe a rewriting of SPARQL query answering under OWL 2 QL into Datalog ± .  ... 
dblp:conf/amw/AhmetajFPSS15 fatcat:m7pltyinqrhh5ok6wuvmafu2wa

Querying OWL 2 QL ontologies under the SPARQL Metamodeling Semantics Entailment Regime

Gianluca Cima, Giuseppe De Giacomo, Maurizio Lenzerini, Antonella Poggi
2017 Sistemi Evoluti per Basi di Dati  
Indeed, SPARQL queries over OWL 2 QL, under the so-called Direct Semantics Entailment Regime, may comprise any assertion expressible in the language, i.e., both ABox atoms and TBox atoms, including inequalities  ...  OWL 2 QL is the profile of OWL 2 targeted to Ontology-Based Data Access (OBDA) scenarios, where large amount of data are to be accessed, and thus answering conjunctive queries over data is the main task  ...  The most typical SPARQL Entailment Regime for OWL 2 QL ontologies is the Direct Semantics Entalment Regime (DSER).  ... 
dblp:conf/sebd/CimaGLP17 fatcat:paygaudv35eojd6ela5mavykxa

On the SPARQL Direct Semantics Entailment Regime for OWL 2 QL

Antonella Poggi
2016 International Workshop on Description Logics  
Thus, in this paper, we investigate query answering over OWL 2 QL under DSER.  ...  Finally, we investigate query answering under a new SPARQL entailment regime, called Direct Semantics Answering Regime (DSAR), obtained by modifying DSER in such a way that existentially quantified variables  ...  Acknowledgements We gratefully acknowledge support by the MIUR under the SIR project MODEUS (RBSI14TQHQ), and by Regione Lazio under the project MAGISTER.  ... 
dblp:conf/dlog/Poggi16 fatcat:xi7qhubxo5eg3hiy7ww7unkj6e

Ontology-Based Integration of Cross-Linked Datasets [chapter]

Diego Calvanese, Martin Giese, Dag Hovland, Martin Rezk
2015 Lecture Notes in Computer Science  
In this paper we tackle the problem of answering SPARQL queries over virtually integrated databases.  ...  This is partly because the OWL built-in owl:sameAs property, the most natural representation of links between data sets, is not included in OWL 2 QL, the de facto ontology language for OBDA.  ...  SPARQL Entailment Regime We present now the standard W3C semantics for SPARQL queries over OWL 2 ontologies under different entailment regimes.  ... 
doi:10.1007/978-3-319-25007-6_12 fatcat:rkm7obtudvgrtfrq5r6pynfuuq

Towards Reconciling SPARQL and Certain Answers

Shqiponja Ahmetaj, Wolfgang Fischl, Reinhard Pichler, Mantas Šimkus, Sebastian Skritek
2015 Proceedings of the 24th International Conference on World Wide Web - WWW '15  
For OWL 2 QL entailment, we present algorithms for the evaluation of an interesting fragment of SPARQL (the so-called well-designed SPARQL).  ...  However, the semantics of query answering under SPARQL entailment regimes is defined in a more naive and much less expressive way than the certain answer semantics usually adopted in DLs.  ...  In [1] , the authors describe a rewriting of SPARQL query answering under OWL 2 QL into Datalog ± .  ... 
doi:10.1145/2736277.2741636 dblp:conf/www/AhmetajFPSS15 fatcat:3f2254oh7jhqdf7lptvsjefyae

Efficient Ontology-Based Data Integration with Canonical IRIs [chapter]

Guohui Xiao, Dag Hovland, Dimitris Bilidas, Martin Rezk, Martin Giese, Diego Calvanese
2018 Lecture Notes in Computer Science  
Formally, we present our approach as a new SPARQL entailment regime and compare it with the sameAs approach.  ...  In ontologybased data integration (OBDI) an ontology provides a coherent view of multiple databases, and SPARQL queries over the ontology are rewritten into (federated) SQL queries over the underlying  ...  This research is supported by the project OBATS, funded by Free University of Bozen-Bolzano, by the Euregio IPN12 KAOS, funded by the "European Region Tyrol-South Tyrol-Trentino" (EGTC) under the first  ... 
doi:10.1007/978-3-319-93417-4_45 fatcat:wounev4lmvbyvfk5xhckcaeqfe

Advancing the Enterprise-class OWL Inference Engine in Oracle Database

Zhe Wu, Karl Rieb, George Eadon, Ankesh Khandelwal, Vladimir Kolovski
2012 International Workshop on OWL Reasoner Evaluation  
In this paper, we discuss our recent implementation and optimization techniques for query-rewrite based OWL 2 QL reasoning, named graph-based inference (local inference), and integration with external  ...  Having a solid OWL reasoning engine inside a relational database system like Oracle is significant because 1) many relational techniques, including query optimization, compression, partitioning, and parallel  ...  We thereby adopt, in addition to ER, another entailment regime for Abox queries to OWL 2 QL ontologies, namely OWL 2 QL Entailment Regime (QLER).  ... 
dblp:conf/ore/WuREKK12 fatcat:isinrkr7zzekdg7yc2ji4fzgl4

Ontop: Answering SPARQL queries over relational databases

Diego Calvanese, Benjamin Cogrel, Sarah Komla-Ebri, Roman Kontchakov, Davide Lanti, Martin Rezk, Mariano Rodriguez-Muro, Guohui Xiao, Óscar Corcho
2016 Semantic Web Journal  
exploiting all elements of the OBDA architecture, its compliance to all relevant W3C recommendations (including SPARQL queries, R2RML mappings, and OWL 2 QL and RDFS ontologies), and its support for all  ...  major relational databases.  ...  This article is supported by the EU under the large-scale integrating project (IP) Optique (Scalable End-user Access to Big Data), grant agreement n. FP7-318338.  ... 
doi:10.3233/sw-160217 fatcat:mjwgfop5tvfvpf3rr6flpfvmwq

FRaQuE: A Framework for Rapid Query Processing Evaluation

Jean-Rémi Bourguet, Luca Pulina
2013 International Workshop on OWL Reasoner Evaluation  
In this paper we present FRaQuE (Framework for Rapid Query Processing Evaluation).  ...  The main purpose of FRaQuE is to offer to a non-expert user a "push-button" solution aimed to help her to evaluate query processors for Ontology Based Data Access, focusing only on input and output data  ...  Under the second regime, we focus on the notion of entailment for the semantics of OWL 2 QL.  ... 
dblp:conf/ore/BourguetP13 fatcat:bymtx7fjmfbsvmrv2vt7oy4w7m

A Datalog-Based Language for Querying RDF Graphs

Marcelo Arenas, Georg Gottlob, Andreas Pieris
2016 Alberto Mendelzon Workshop on Foundations of Data Management  
To the best of our knowledge, the only language that supports the above features, focussing on the profile OWL 2 QL of OWL 2, while its query evaluation problem is tractable in data complexity, is the  ...  However, there are still useful queries that cannot be expressed in SPARQL 1.1, due to the lack of general recursion [14] .  ...  Arenas is funded by the Millenium Nucleus Center for Semantic Web Research under grant NC120004.  ... 
dblp:conf/amw/ArenasGP16 fatcat:oiwppq73hbfxzj3rnxkpx4py2m

Schema-Agnostic Query Rewriting in SPARQL 1.1 [chapter]

Stefan Bischof, Markus Krötzsch, Axel Polleres, Sebastian Rudolph
2014 Lecture Notes in Computer Science  
SPARQL 1.1 supports the use of ontologies to enrich query results with logical entailments, and OWL 2 provides a dedicated fragment OWL QL for this purpose.  ...  This allows us to query RDF data under OWL QL entailment without extracting or preprocessing OWL axioms.  ...  The answers of a conjunctive query q over an OWL QL ontology G are exactly the answers of the SPARQL 1.1 query Rewrite(q) over G under simple entailment.  ... 
doi:10.1007/978-3-319-11964-9_37 fatcat:ytt3lolq75bqfgmyhaijhiarzm

The Ontop Framework for Ontology Based Data Access [chapter]

Timea Bagosi, Diego Calvanese, Josef Hardi, Sarah Komla-Ebri, Davide Lanti, Martin Rezk, Mariano Rodríguez-Muro, Mindaugas Slusnys, Guohui Xiao
2014 Communications in Computer and Information Science  
The main functionality of OBDA systems is query answering.  ...  Usually, the conceptual layer is expressed in the form of an RDF(S) [10] or OWL [15] ontology, and the data is stored in relational databases.  ...  This paper is supported by the EU under the large-scale integrating project (IP) Optique (Scalable End-user Access to Big Data), grant agreement n. FP7-318338.  ... 
doi:10.1007/978-3-662-45495-4_6 fatcat:77pqwm6dznf5nexppacg2oxfxa

Optimizing Query Answering over OWL Ontologies [chapter]

Ilianna Kollia
2011 Lecture Notes in Computer Science  
That is why, when the schema of an ontology is written in a highly expressive language like OWL 2 DL, currently used query answering systems do not find all answers to queries posed over the ontology,  ...  Query answering is a key reasoning task for many ontology based applications in the Semantic Web. Unfortunately for OWL, the worst case complexity of query answering is very high.  ...  OWL entailment relation (the OWL entailment regime of SPARQL [5] ).  ... 
doi:10.1007/978-3-642-21064-8_45 fatcat:kumdiz4vhfahvd7mqyt7yhlivq

Answering Queries over OWL Ontologies with SPARQL

Ilianna Kollia, Birte Glimm, Ian Horrocks
2011 W3C Web Ontology Language (OWL) Experiences and Directions Workshop (OWLED)  
The SPARQL query language is currently being extended by W3C with so-called entailment regimes, which define how queries are evaluated under more expressive semantics than SPARQL's standard simple entailment  ...  We describe a sound and complete algorithm for the OWL Direct Semantics entailment regime.  ...  SPARQL-OWL Query Answering We first give a brief introduction to the SPARQL-OWL entailment regime and then describe an algorithm that finds answers to queries under this regime.  ... 
dblp:conf/owled/KolliaGH11 fatcat:h5rjf4oua5aybje3agyxfs2ccu
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