@conference {362, title = {The Combined Approach to Query Answering Beyond the OWL 2 Profiles}, booktitle = {Proceedings of the 24th International Joint Conference on Artificial Intelligence (IJCAI)}, year = {2015}, abstract = {

Combined approaches have become a successful technique for CQ answering over ontologies. Existing algorithms, however, are restricted to the logics underpinning the OWL 2 profiles. Our goal is to make combined approaches applicable to a wider range of ontologies. We focus on RSA: a class of Horn ontologies that extends the profiles while ensuring tractability of standard reasoning. We show that CQ answering over RSA ontologies without role composition is feasible in NP. Our reasoning procedure generalises the combined approach for ELHO and DL-LiteR using an encoding of CQ answering into fact entailment w.r.t. a logic program with function symbols and stratified negation. Our results have significant practical implications since many out-of-profile Horn ontologies are RSA.

}, url = {http://www.cs.ox.ac.uk/isg/people/cristina.feier/ijcai_rsafinal.pdf}, author = {Cristina Feier and David Carral and Giorgio Stefanoni and Cuenca Grau, Bernardo and Ian Horrocks} } @conference {363, title = {Extending the Combined Approach Beyond Lightweight Description Logics}, booktitle = {Proceedings of the 28th International Workshop on Description Logics (DL)}, year = {2015}, abstract = {

Combined approaches have become a successful technique for CQ answering over ontologies. Existing algorithms, however, are restricted to the logics underpinning the OWL 2 profiles. Our goal is to make combined approaches applicable to a wider range of ontologies. We focus on RSA: a class of Horn ontologies that extends the profiles while ensuring tractability of standard reasoning. We show that CQ answering over RSA ontologies without role composition is feasible in NP. Our reasoning procedure generalises the combined approach for ELHO and DL-LiteR using an encoding of CQ answering into fact entailment w.r.t. a logic program with function symbols and stratified negation. Our results are significant in practice since many out-of-profile Horn ontologies are RSA.

}, url = {http://www.cs.ox.ac.uk/isg/people/cristina.feier/pdfs/dlmain.pdf}, author = {Cristina Feier and David Carral and Giorgio Stefanoni and Cuenca Grau, Bernardo and Ian Horrocks} } @conference {135, title = {EL-ifying Ontologies}, booktitle = {Automated Reasoning - 7th International Joint Conference, IJCAR 2014, Held as Part of the Vienna Summer of Logic, {VSL} 2014, Vienna, Austria, July 19-22, 2014. Proceedings}, year = {2014}, pages = {464{\textendash}479}, abstract = {

The OWL 2 profiles are fragments of the ontology language OWL 2 for which standard reasoning tasks are feasible in polynomial time. Many OWL ontologies, however, contain a typically small number of out-of-profile axioms, which may have little or no influence on reasoning outcomes. We investigate techniques for rewriting axioms into the EL and RL profiles of OWL 2. We have tested our techniques on both classification and data reasoning tasks with encouraging results.

}, keywords = {description logics, OWL, Rewriting, Tractable Reasoning}, doi = {10.1007/978-3-319-08587-6_36}, url = {http://dx.doi.org/10.1007/978-3-319-08587-6_36}, author = {David Carral and Cristina Feier and Cuenca Grau, Bernardo and Pascal Hitzler and Ian Horrocks} } @conference {131, title = {Pushing the Boundaries of Tractable Ontology Reasoning}, booktitle = {The Semantic Web - ISWC 2014 - 13th International Semantic Web Conference, Riva del Garda, Italy, October 19-23, 2014. Proceedings, Part II}, year = {2014}, pages = {148{\textendash}163}, abstract = {

We identify a class of Horn ontologies for which standard reasoning tasks such as instance checking and classification are tractable. The class is general enough to include the OWL 2 EL, QL, and RL profiles. Verifying whether a Horn ontology belongs to the class can be done in polynomial time. We show empirically that the class includes many real-world ontologies that are not included in any OWL 2 profile, and thus that polynomial time reasoning is possible for these ontologies.

}, keywords = {description logics, OWL, Tractable Reasoning}, doi = {10.1007/978-3-319-11915-1_10}, url = {http://dx.doi.org/10.1007/978-3-319-11915-1_10}, author = {David Carral and Cristina Feier and Cuenca Grau, Bernardo and Pascal Hitzler and Ian Horrocks} } @conference {134, title = {Is Your Ontology as Hard as You Think? Rewriting Ontologies into Simpler DLs}, booktitle = {Informal Proceedings of the 27th International Workshop on Description Logics, Vienna, Austria, July 17-20, 2014.}, year = {2014}, pages = {128{\textendash}140}, abstract = {

We investigate cases where an ontology expressed in a seemingly hard DL can be polynomially reduced to one in a simpler logic, while preserving reasoning outcomes for classification and fact entailment. Our transformations target the elimination of inverse roles, universal and existential restrictions, and in the best case allow us to rewrite the given ontology into one of the OWL 2 profiles. Even if an ontology cannot be fully rewritten into a profile, in many cases our transformations allow us to exploit further optimisation techniques. Moreover, the elimination of some out-of-profile axioms can improve the performance of modular reasoners, such as MORe. We have tested our techniques on both classification and data reasoning tasks with encouraging results.

}, keywords = {description logics, OWL, Tractable Reasoning}, url = {http://ceur-ws.org/Vol-1193/paper_75.pdf}, author = {David Carral and Cristina Feier and Ana Armas Romero and Cuenca Grau, Bernardo and Pascal Hitzler and Ian Horrocks} } @conference {154, title = {Optique 1.0: Semantic Access to Big Data: The Case of Norwegian Petroleum Directorate{\textquoteright}s FactPages}, booktitle = {Proceedings of the ISWC 2013 Posters \& Demonstrations Track, Sydney, Australia, October 23, 2013}, volume = {1035}, year = {2013}, pages = {65{\textendash}68}, publisher = {CEUR-WS.org}, organization = {CEUR-WS.org}, author = {Evgeny Kharlamov and Martin Giese and Ernesto Jim{\'e}nez-Ruiz and Martin G. Skj{\ae}veland and Ahmet Soylu and Dmitriy Zheleznyakov and Timea Bagosi and Marco Console and Peter Haase and Ian Horrocks and Sarunas Marciuska and Christoph Pinkel and Mariano Rodriguez-Muro and Marco Ruzzi and Valerio Santarelli and Domenico Fabio Savo and Kunal Sengupta and Michael Schmidt and Evgenij Thorstensen and Johannes Trame and Arild Waaler}, editor = {Eva Blomqvist and Tudor Groza} } @conference {111, title = {Ontology Alignment for Linked Open Data}, booktitle = {The Semantic Web - ISWC 2010 - 9th International Semantic Web Conference, ISWC 2010}, volume = {6496}, year = {2010}, pages = {402{\textendash}417}, publisher = {Springer}, organization = {Springer}, address = {Shanghai, China}, abstract = {

The Web of Data currently coming into existence through the Linked Open Data (LOD) effort is a major milestone in realizing the Semantic Web vision. However, the development of applications based on LOD faces difficulties due to the fact that the different LOD datasets are rather loosely connected pieces of information. In particular, links between LOD datasets are almost exclusively on the level of instances, and schema-level information is being ignored. In this paper, we therefore present a system for finding schema-level links between LOD datasets in the sense of ontology alignment. Our system, called BLOOMS, is based on the idea of bootstrapping information already present on the LOD cloud. We also present a comprehensive evaluation which shows that BLOOMS outperforms state-of-the-art ontology alignment systems on LOD datasets. At the same time, BLOOMS is also competitive compared with these other systems on the Ontology Evaluation Alignment Initiative Benchmark datasets.

}, doi = {10.1007/978-3-642-17746-0_26}, url = {http://dx.doi.org/10.1007/978-3-642-17746-0_26}, author = {Prateek Jain and Pascal Hitzler and Amit Sheth and Kunal Verma and Peter Z. Yeh}, editor = {Peter F. Patel-Schneider and Yue Pan and Pascal Hitzler and Peter Mika and Lei Zhang and Jeff Z. Pan and Ian Horrocks and Birte Glimm} } @proceedings {299, title = {The Semantic Web - ISWC 2010. 9th International Semantic Web Conference, ISWC 2010, Shanghai, China, November 7-11, 2010, Revised Selected Papers, Part II}, journal = {9th International Semantic Web Conference, ISWC 2010}, volume = {6497}, year = {2010}, publisher = {Springer}, address = {Shanghai, China}, editor = {Peter F. Patel-Schneider and Yue Pan and Pascal Hitzler and Peter Mika and Lei Zhang and Jeff Z. Pan and Ian Horrocks and Birte Glimm} } @proceedings {298, title = {The Semantic Web - ISWC 2010. 9th International Semantic Web Conference, ISWC 2010, Shanghai, China, November 7-11, 2010, Revised Selected Papers, Part I}, journal = {9th International Semantic Web Conference, ISWC 2010}, volume = {6496}, year = {2010}, publisher = {Springer}, address = {Shanghai, China}, editor = {Peter F. Patel-Schneider and Yue Pan and Pascal Hitzler and Peter Mika and Lei Zhang and Jeff Z. Pan and Ian Horrocks and Birte Glimm} }