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Dr. Giorgos Stoilos
 
Giorgos Stoilos   Research Associate
Electrical & Computer Engineering

Marie Curie CIG Fellow

gstoil --> image.ntua.gr
Full CV [Greek], [English]


Interests Biography Distinctions Publications Research Projects Software
Interests

My research interests include most aspects of knowledge representation and automated reasoning, especially focused on Description Logics (DLs) and ontology languages, such as OWL, as well as their application in areas like the Semantic Web and Multimedia. Recently I work on the topic of automatic evaluation and benchmarking of Description Logic and Semantic Web query answering systems, where I have designed and developed methods for the automatic generation of synthetic testing data and conjunctive queries. Most algorithms have been implemented in the prototype tool SyGENiA. Furthermore, I am also working on query rewriting over DL ontologies where I have designed and developed a new query rewriting system called IQAROS. While in Oxford, I participated in the development of the HermiT reasoner, where I developed HermiT's new optimised classification algorithm. Additionally, I am also currently working on semantic approximation techniques and scalable query answering over expressive ontologies.

During my PhD I also worked on the problem of representing and reasoning with fuzzy knowledge, where I have developed fuzzy extensions of Description Logics and of OWL, as well as a number of tableaux reasoning algorithms for them that have been implemented in the FiRE fuzzy reasoner. Last but not least, I have also worked in the area of Ontology Alignment and semantic interoperability, where I have developed a new String Matching method, called I-Sub, which has been integrated in several popular Ontology Alignment and Schema Matching Systems, and recently in the NLP package of SWI-prolog.

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Biography

I was born in Athens in July 1981. In 2003 I received my Certificate in Computer Science from the Department of Computer Science and Telecommunication, National and Kapodistrian University of Athens. Then, at the same year I joined the Image, Video and Multimedia Laboratory (IVML), of the School of Electrical and Computer Engineering , National and Technical University of Athens to study towards a PhD degree, which I successfully defended in February 2008. Then, I worked as a project manager and work package leader for 1 year in IVML which I left in May 2009 to join the Information Systems Group of the Department of Computer Science at the University of Oxford. I worked there for 2.5 years and in January 2012 I rejoined the group at IVML. Since April 2012 I hold a Marie Curie Career Reintegration Grant from European Union’s Seventh Framework Programme (FP7/2007- 2013) [Marie Curie Actions].

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Distinctions - Academic Achievements

  • Marie Curie Career Integration Grant (2012-2016).

  • Description Logic Steering Committee member for years 2012-2015.

  • AAAI 2010 outstanding paper award for the paper "How Incomplete is Your Semantic Web Reasoner".

  • Two ISWC 2010 nominees for best paper award for the papers "Completeness Guarantees for Incomplete Reasoners" and for "Optimising Ontology Classification".

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  • The Chorafas Institute prize for best PhD Dissertation in NTUA, 2008.

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  • PENED: Doctoral Scholarship from the Greek Secreteriat of Research and Technology (2005-2008).
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    Research Projects

    2012-2016
    SCoRE (Marie Curie Grant FP7/2007- 2013) 303914) - Scalable and Complete Ontology Reasoning.
    2009-2011 HermiT reasoner (EPSRC Grand EP/F065841/1) - Hypertalbeaux Reasoning for Large Ontologies.
    2009-2011 SEALS (RI238975-CPCSA) - Semantic Evaluation at Large Scale.
    2006-2009 x-Media (IST-026978-IP) - Large Scale Knowledge Sharing and Reuse Across Media.
    2007-2009 Boemie (IST-027538-STREP) - Bootstrapping Ontology Evolution with Multimedia Information Extraction
    2006-2008 K-Space (IST-027026-NOE) - Knowledge Space of Semantic Inference for Automatic Annotation and Retrieval of Multimedia Content
    2004-2007 Knowledge Web (IST-507482-NOE) - Realizing the Semantic Web, Semantic-Based Knowledge Systems.
    2004-2005 aceMedia - Integrating Knowledge, Semantics and Content for User-Centred Intelligent Media Services
    2004-2005 Cinegram - A System for characterization, management and access to Audio-Visual Databases
    2002-2003 PoLoS - An Integrated Platform for Location Based Services

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    Software

  • Hydrowl: A Hybrid Query Answering System for OWL Ontologies.

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  • IQAROS: A Query rewriting systems for OWL 2 QL (DL-Lite) ontologies.

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  • HermiT: A Hypertableaux reasoner for OWL 2 Ontologies.

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  • SyGENiA: A Synthetic Generator for Ontology facts (assertions) and Conjunctive Queries for evaluating Semantic Web reasoners.

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  • I-Sub: A String similarity measure for computing similarities between strings (something like the Levenshtein distance). The theory and evaluation of the method can be found in the paper A String Metric for Ontology Alignment. See also SWI-Prolog.

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  • FiRE: A Beta Reasoner for the Fuzzy Description Logic f-SHI has been developed in our lab
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    Publications

    See also a list of my publications (possibly) with citation analysis at DBLP, Google Scholar, Microsoft Academic Research, and Arnetminer
    2014 2013
    2012 2011
    2010 2009
    2008 2007
    2006 2005
    Publications • 2014
    59.   Giorgos Stoilos
    Hydrowl: A Hybrid Query Answering System for OWL 2 DL Ontologies [CONFERENCE]
    In Proceedings of the 8th International Conference on Web Reasoning and Rule Systems (RR 2014), Athens, Greece.
    [.pdf | .bib]
     
    58.   Giorgos Stoilos
    OBDA Using RL Reasoners and Repairing [CONFERENCE]
    In Proceedings of the 27th International Workshop on Description Logics (DL 2014), Vienna, Austria.
    [.pdf | .bib]
     
    57.   Giorgos Stoilos and Giorgos Stamou
    Hybrid Query Answering Over DL Ontologies [CONFERENCE]
    In Proceedings of the 27th International Workshop on Description Logics (DL 2014), Vienna, Austria.
    [.pdf | .bib]
     
    56.   Giorgos Stoilos and Giorgos Stamou
    Hybrid Query Answering Over OWL Ontologies [CONFERENCE]
    In Proceedings of the 21st European Conference on Artificial Intelligence (ECAI 2014), 2014.
    [.pdf | .bib]
     
    55.   Birte Glimm, Ian Horrocks, Boris Motik, Giorgos Stoilos, and Zhe Wang
    HermiT: An OWL 2 Reasoner [JOURNAL]
    Journal of Automated Reasoning (JAR), In Press, 2014.
    [.pdf | .bib]
     
    54.   Giorgos Stoilos
    Ontology-Based Data Access Using Rewriting, OWL 2 RL Systems and Repairing
    In Proceedings of the 11th European Semantic Web Conference (ESWC 2014), 2014. [CONFERENCE]
    [.pdf | .bib]
     
    53.   Tassos Venetis, Giorgos Stoilos, and Giorgos Stamou
    Query rewriting under query refinements [JOURNAL]
    Journal of Knowledge-Based Systems, p. 36-48, v. 56, 2014.
    [.pdf | .bib]
     
    52.   Tassos Venetis, Giorgos Stoilos, and Giorgos Stamou
    Query Extensions and Incremental Query Rewriting for OWL 2 QL Ontologies [JOURNAL]
    Journal on Data Semantics, v.3(1), p. 1-23, 2014.
    [.pdf | .bib]
     
    51.   Giorgos Stoilos and Giorgos Stamou
    Reasoning with Fuzzy Extensions of OWL and OWL 2 [JOURNAL]
    Journal of Knowledge and Information Systems (KAIS), Accepted.
    [.pdf | .bib]
     
    Publications • 2013
    50.   Despoina Trivela, Giorgos Stoilos, Alexandros Chortaras and Giorgos Stamou
    Optimising Resolution-Based Rewriting Algorithms for DL Ontologies [WORKSHOP]
    In Proceedings of the 26th Workshop on Description Logics (DL 2013).
    [.pdf | .bib]
     
    49.   Eleni Tsalapati, Giorgos Stoilos, Giorgos Stamou, and George Koletsos
    Query Rewriting Under Ontology Evolution [WORKSHOP]
    In Proceedings of the 26th Workshop on Description Logics (DL 2013).
    [.pdf | .bib]
     
    48.   Bernardo Cuenca Grau, Boris Motik, Giorgos Stoilos and Ian Horrocks
    Computing Datalog Rewritings beyond Horn Ontologies [CONFERENCE]
    In Proceedings of the 23rd International Joint Conference on Artificial Intelligence (IJCAI-2013).
    [.pdf | .bib | TR (pdf)]
     
    47.   N. Simou, G. Stoilos, and G. Stamou
    Storing and Querying Fuzzy Knowledge in the Semantic Web Using FiRE [BOOK]
    In Fernando Bobillo, Paulo CG Costa, et al. (eds) Uncertainty Reasoning for the Semantic Web II (Book).
    [.pdf | .bib]
     
    Publications • 2012
    46.   Theofilos Mailis, Giorgos Stoilos, Nikos Simou, Giorgos Stamou, and Stefanos Kollias
    Tractable reasoning with vague knowledge using fuzzy EL++ [JOURNAL]
    Journal of Intelligent Information Systems, v. 39, p. 399-440, 2012.
    [DOI | .bib]
     
    45.   Eleni Tsalapati, Giorgos Stoilos, Giorgos Stamou, and George Koletsos
    Query Rewriting Under Ontology Contraction [CONFERENCE]
    In Proceedings of the 6th International Conference on Web Reasoning and Rule Systems (RR2012), 2012.
    [.pdf | .bib]
     
    44.   Bernardo Cuenca Grau, Boris Motik, Giorgos Stoilos and Ian Horrocks
    Completeness Guarantees for Incomplete Ontology Reasoners: Theory and Practice [JOURNAL]
    Journal of Artificial Intelligence Research, v. 43, p. 419-476, 2012.
    [.pdf | .bib]
     
    43.   Birte Glimm‚ Ian Horrocks‚ Boris Motik, Rob Shearer and Giorgos Stoilos
    A Novel Approach to Ontology Classification [JOURNAL]
    Journal of Web Semantics: Science‚ Services and Agents on the World Wide Web‚ v. 14, p. 84-101, 2012.
    [DOI | .bib]
     
    42.   Martha Imprialou, Giorgos Stoilos and Bernardo Cuenca Grau
    Benchmarking Ontology-based Query Rewriting Systems [CONFERENCE]
    In Proceedings of the 26th AAAI Conference on Artificial Intelligence (AAAI 2012)
    [.pdf | .bib]
     
    41.   T. Venetis, G. Stoilos, G. Stamou
    Incremental Query Rewriting for OWL 2 QL [WORKSHOP]
    25th International Workshop on Description Logics (DL2012)
    [.pdf | .bib]
     
    Publications • 2011
    40.   Bernardo Cuenca Grau and Giorgos Stoilos
    What to ask to an incomplete Semantic Web reasoner? [CONFERENCE]
    In Proceedings of the 22nd International Joint Conference on Artificial Intelligence (IJCAI−2011). Pages 2226−2231. 2011.
    [.pdf | .bib]
     
    39.   Giorgos Stoilos‚ Bernardo Cuenca Grau‚ Boris Motik and Ian Horrocks
    Repairing Ontologies for Incomplete Reasoners [CONFERENCE]
    In Proceedings of the 10th International Semantic Web Conference (ISWC 2011). Springer LNCS. 2011.
    [.pdf | .bib]

    Watch the presentation given at ISWC 2011
     
    38.   Giorgos Stoilos and Bernardo Cuenca Grau
    Repairing Incomplete Reasoners [CONFERENCE]
    In Proceedings of the 24th International Workshop on Description Logics (DL 2011). CEUR. 2011
    [.pdf | .bib]
     
    37.   T. Venetis, G. Stoilos, G. Stamou
    Query Rewriting Under Query Extensions for OWL 2 QL Ontologies [WORKSHOP]
    In Proceedings of the 7th International Workshop on Scalable Semantic Web Knowledge Base Systems (SSWS2011).
    [.pdf | .bib]
     
    36.   Kalliopi Dalakleidi, Stamatia Dassiopoulou, Giorgos Stoilos, Vassilis Tzouvaras, Giorgos Stamou and Yiannis Kompatsiaris
    Semantic Representation of Multimedia Content [BOOK]
    Paliouras G., Spyropoulos C., Tsatsaronis G. (eds), Knowledge-Driven Multimedia Extraction and Ontology Evolution, Springer
    [.pdf | .bib]
     
    35.   N. Simou, G. Stoilos, C. Saathoff, J. Nemrava, V. Svatek, P. Berka, V. Tzouvaras
    Reasoning for multimedia analysis [BOOK]
    R. Troncy, B. Huet and S. Schenk (eds.), Multimedia Semantics: Metadata, Analysis and Interaction, Wiley, 2011
    [DOI | .bib]
     
    Publications • 2010
    34.   Birte Glimm‚ Ian Horrocks‚ Boris Motik and Giorgos Stoilos
    Optimising Ontology Classification [CONFERENCE]
    In Proceedings of the 9th International Semantic Web Conference (ISWC 2010).
    Vol. 6496 of LNCS. Pages 225−240. Springer Verlag. 2010.
    Nominated for ISWC 2010 Best Paper
    [.pdf | .bib]
     
    33.   Giorgos Stoilos‚ Bernardo Cuenca Grau and Ian Horrocks
    Completeness Guarantees for Incomplete Reasoners [CONFERENCE]
    In Proceedings of the 9th International Semantic Web Conference (ISWC 2010).
    Nominated for ISWC 2010 Best Paper
    [.pdf | .bib]
     
    32.   Giorgos Stoilos, Bernardo Cuenca Grau, and Ian Horrocks
    How Incomplete is your Semantic Web Reasoner? [CONFERENCE]
    In Proceedings of the 24th AAAI Conference on Artificial Intelligence (AAAI 2010), Pages 1431−1436. AAAI Press. 2010.
    Outstanding Paper Award Winner
    [.pdf | .bib]

    Watch the presentation given at AAAI 2010
     
    31.   N. Simou, T. Mailis, G. Stoilos and G. Stamou
    Optimization Techniques for Fuzzy Description Logics [WORKSHOP]
    23rd International Workshop on Description Logics (DL 10), Waterloo, Canada, 2010
    [.pdf | .bib]
     
    30.   Giorgos Stoilos, Jeff Z. Pan and Giorgos Stamou
    Fuzzy extensions of OWL: Logical properties and reduction to fuzzy description logics [JOURNAL]
    International Journal of Approximate Reasoning (IJAR), 2010.
    [DOI | .bib]
     
    29.   T. Mailis, G. Stoilos, G. Stamou
    Expressive reasoning with horn rules and fuzzy description logics [JOURNAL]
    Knowledge and Information Systems, Volume 25, Number 1, 105-136, 2010
    [.pdf | .bib]
     
    Publications • 2009
    28.   Giorgos Stoilos and Giorgos Stamou
    A Framework for Reasoning with Expressive Continuous Fuzzy Description Logics [WORKSHOP]
    22nd International Workshop on Description Logics (DL-09), Oxford
    [.pdf | .bib]
     
    27.   G. Stoilos, G. Stamou, and J.Z. Pan
    Scalable Reasoning with Tractable Fuzzy Ontology Languages [BOOK]
    In Anne Laurent and Marie-Jeanne Lesot (Eds.) Scalable Fuzzy Algorithms for Data Management and Analysis: Methods and Design, IGI Global, 2009
    [DOI | .bib]
     
    Publications • 2008
    26.   C.V. Damasio, J.Z. Pan, G. Stoilos, and U. Straccia
    Representing Uncertainty Rules in RuleML [JOURNAL]
    Fundamenta Informaticae, Vol. 82, p. 1-24, 2008
    [.pdf | .bib]
     
    25.   N. Simou, Th. Athanasiadis, G. Stoilos, S. Kollias
    Image Indexing and Retrieval using Expressive Fuzzy Description Logics [JOURNAL]
    Signal, Image and Video Processing, Springer, Volume 2, Number 4, pp. 321-335, December 2008
    [DOI | .bib]
     
    24.   A. Ferrara, D. Lorusso, G. Stamou, G. Stoilos, V. Tzouvaras, T. Venetis
    Resolution of conflicts among ontology mappings: a fuzzy approach [WORKSHOP]
    International Workshop on Ontology Matching (OM2008), Karlsruhe, October 26, 2008
    [.pdf | .bib]
     
    23.   G. Stoilos, G. Stamou and S. Kollias
    Reasoning with Qualified Cardinality Restrictions in Fuzzy Description Logics [CONFERENCE]
    In Proceedings of the IEEE International Conference on Fuzzy Systems (Fuzz-IEEE 08)
    [.pdf | .bib]
     
    22.   G. Stoilos, G. Stamou, J.Z. Pan
    Classifying Fuzzy Subsumption in Fuzzy-EL+ [WORKSHOP]
    21st International Workshop on Description Logics (DL 08), Dresden, Germany, 2008
    [.pdf | .bib]
     
    21.   Jeff Z. Pan, Giorgos Stamou, Giorgos Stoilos, Edward Thomas, and Stuart Taylor
    Scalable Querying Services over Fuzzy Ontologies [CONFERENCE]
    In Proceedings of the 17th International World Wide Web Conference (WWW 08), Beijing, 2008
    [.pdf | .bib]
     
    20.   N. Simou, G. Stoilos, V. Tzouvaras, G. Stamou, S. Kollias
    Storing and Querying Fuzzy Knowledge in the Semantic Web [WORKSHOP]
    7th International Workshop on Uncertainty Reasoning For the Semantic Web, Karlsruhe, Germany, October 2008
    [.pdf | .bib]
     
    19.   P. Cimiano, P. Haase, Q. Ji, T. Mailis, G. Stamou, G. Stoilos, T. Tran, V. Tzouvaras
    Reasoning with Large A-Boxes in Fuzzy Description Logics using DL reasoners: An experimental evaluation [WORKSHOP]
    Workshop on Advancing Reasoning on the Web: Scalability and Commonsense
    [.pdf | .bib]
     
    18.   G. Stoilos, G Stamou, J.Z. Pan, N. Simou and V. Tzouvaras
    Reasoning with the Fuzzy Description Logic f-SHIN: Theory, Practice and Applications [BOOK]
    In Paulo CG Costa, Claudia d'Amato et al. (eds) Uncertainty Reasoning for the Semantic Web I (Book)
    [.pdf | .bib]
     
    17.   T. Mailis, G. Stoilos, N. Simou, G. Stamou
    Tractable Reasoning Based on the Fuzzy EL++ Algorithm [WORKSHOP]
    7th International Workshop on Uncertainty Reasoning For the Semantic Web, Karlsruhe, Germany, October 2008
    [.pdf | .bib]
     
    Publications • 2007
    16.   G. Stoilos, G. Stamou, J.Z. Pan, V. Tzouvaras, I. Horrocks
    Reasoning with Very Expressive Fuzzy Description Logics [JOURNAL]
    Journal of Artificial Intelligence Research, 30, 8, 273-320
    [.pdf | .bib]
     
    15.   G. Stoilos and G. Stamou
    Extending Fuzzy Description Logics for the Semantic Web [WORKSHOP]
    3rd International Workshop of OWL: Experiences and Directions, Innsbruck, 2007
    [.pdf | .bib]
     
    14.   Jeff Z. Pan, Giorgos Stamou, Giorgos Stoilos, and Edward Thomas
    Expressive Querying over Fuzzy DL-Lite Ontologies [WORKSHOP]
    20th International Workshop on Description Logics, Brixen-Bressanone, Italy, 2007
    [.pdf | .bib]
     
    13.   T. Mailis, G. Stoilos, G. Stamou
    Expressive Reasoning with Horn Rules and Fuzzy Description Logics [CONFERENCE]
    In Proceedings of the 1st International Conference on Web Reasoning and Rule Systems, Innsbruck (Austria)
    [.pdf | .bib]
     
    12.   T. Venetis, G. Stoilos, G. Stamou and S. Kollias
    f-DLPs: Extending Description Logic Programs with Fuzzy Sets and Fuzzy Logic [CONFERENCE]
    IEEE International Conference on Fuzzy Systems (Fuzz-IEEE' 07), London, 2007
    [.pdf | .bib]
     
    Publications • 2006
    11.   G. Stoilos, N. Simou, G. Stamou and S. Kollias
    Uncertainty and the Semantic Web [JOURNAL]
    IEEE Intelligent Systems, 21(5), p. 84-87, 2006
    [.pdf | .bib]
     
    10.   Jeff Z. Pan, Giorgos Stoilos, Giorgos Stamou, Vassilis Tzouvaras, Ian Horrocks
    f-SWRL: A Fuzzy Extension of SWRL [JOURNAL]
    Data Semantics, special issue on Emergent Semantics, vol. 4090, p. 28-46, 2006
    [.pdf | .bib]
     
    9.   Carlos Damasio, Jeff Pan, Giorgos Stoilos, Umberto Straccia
    An Approach to Representing Uncertainty Rules in RuleML [CONFERENCE]
    In Proceedings of the 2nd International Conference on Rules and Rule Markup Languages for the Semantic Web (RuleML-06), 2006
    [.pdf | .bib]
     
    8.   G. Stoilos, G. Stamou, J.Z. Pan
    Handling Imprecise Knowledge with Fuzzy Description Logic [WORKSHOP]
    International Workshop on Description Logics (DL 06), Lake District, UK, 2006
    [.pdf | .bib]
     
    7.   G. Stoilos, U. Straccia, G. Stamou, Jeff Z. Pan
    General Concept Inclusions in Fuzzy Description Logics [CONFERENCE]
    In Proceedings of the 17th European Conference on Artificial Intelligence (ECAI 06), Riva del Garda, Italy, 2006
    [.pdf | .bib]
     
    Publications • 2005
    6.   G. Stoilos, G. Stamou, S. Kollias
    A String Metric For Ontology Alignment [CONFERENCE]
    In Proceedings of the 4th International Semantic Web Conference (ISWC 2005), Galway, 2005
    [.pdf | .bib]
     
    5.   G. Stoilos, G. Stamou, V. Tzouvaras, J.Z. Pan
    Uncertainty and RuleML rulebases: A Preliminary Report [CONFERENCE]
    In Proceedings of the 1st International Conference on Rules and Rule Markup Languages for the Semantic Web, Galway, 2005
    [.pdf | .bib]
     
    4.   G. Stoilos, G. Stamou, V. Tzouvaras, J.Z. Pan, I. Horrocks
    A Fuzzy Description Logic for Multimedia Knowledge Representation [WORKSHOP]
    International Workshop on Multimedia and the Semantic Web
    [.pdf | .bib]
     
    3.   G. Stoilos, G. Stamou, V. Tzouvaras, J.Z. Pan, I. Horrocks
    Fuzzy OWL: Uncertainty and the Semantic Web [WORKSHOP]
    International Workshop of OWL: Experiences and Directions, Galway, 2005
    [.pdf | .bib]
     
    2.   V. Tzouvaras, S. Dasiopoulou, F.M. Recuerda, G. Stoilos, Y. Kompatsiaris, and G. StamouG
    Multimedia Analysis and Annotation Requirements for the Semantic Web. [WORKSHOP]
    European Workshop on the Integration of Knowledge, Semantics and Digital Media Technologies (EWIMT), 2005
    [ .bib]
     
    1.   G. Stoilos, G. Stamou, V. Tzouvaras, J.Z. Pan, I. Horrocks
    The Fuzzy Description Logic f-SHIN [WORKSHOP]
    International Workshop on Uncertainty Reasoning For the Semantic Web (2005).
    [.pdf | .bib]
     
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