Alejandro Llaves

Ontology Engineering Group (OEG)
Facultad de Informática
Departamento de Inteligencia Artificial
Universidad Politécnica de Madrid
Avda. Montepríncipe s/n
Boadilla del Monte, 28660 Madrid, Spain
Tel: +34 913363670
Fax: +34 913524819
Email: allaves(at)

IRTG Research Initiative: Semantic Mediation across Communities and Sensors
Research Title: Integration of Geosensor Data by means of an Event Abstraction Layer
Supervisor: Prof. Dr. Werner Kuhn
Research Group: MUSIL
Funding: ENVISION project (FP7-249170)
Timeframe: November 2009 – November 2013

Research Topic

Information communities conceptualise the world based on their domain knowledge and depending on application purposes. This also applies to the methods used to model and classify changes in the environment. In spatio-temporal modelling, changes can be represented as events. The heterogeneity of representations often causes interoperability problems when such communities exchange geospatial information. To enhance interoperability among diverse communities, it is required to develop models that do not restrict the representation of events, but allow integrating different perspectives on changes in the environment.
We believe that patterns reflected in geosensor data represent changes in the real world, thus they can be modelled as events. In order to address the research challenge of detecting, classifying, and representing such events, an Event Abstraction Layer has been designed. It is powered by a Complex Event Processing engine to analyse data streams. Sensor observations are considered as atomic geospatial events. The detection of higher level events in time series of observations is then reduced to a problem of pattern matching over sliding time windows. The layer also includes an Event-Abstraction ontology which defines the structure of the new generated information. The core concept in our ontology is the EventAbstraction, which represents an observed situation of change in one or various properties of a geographical entity that is relevant for the application domain. The main difference to other event models is that the central concept of the Event-Abstraction ontology does not represent the event itself, but a perspective on what happened in that event, i.e. the description of a situation. Therefore, our model can accommodate multiple views on the same event.
Assuming that event-related domain knowledge is provided, we suggest the creation of lightweight domain ontologies and their alignment to a common foundational ontology, like DOLCE Ultralite. The classification of events as they are detected is realised via the semantic annotation of patterns with links to event types in the domain ontologies. Events are constructed as instances of the Event-Abstraction ontology and linked to the sensor observations they were derived from. Additional information is attached to the event instance, like an inferred spatio-temporal region and the pattern that was used to trigger its detection.

Research Interests

  • Spatio-temporal modelling
  • Event Processing
  • Semantic Sensor Web
  • Environmental monitoring
  • Decision support systems


PhD thesis

  • Llaves, A. (2014): “Integration of Sensor Data by means of an Event Abstraction Layer”. PhD thesis, Westfälische Wilhelms-Universität Münster, Münster, Germany. Link

Journal Articles

  • Llaves, A., & Kuhn, W. (2014): “An Event Abstraction Layer for the Integration of Geosensor Data”. International Journal of Geographical Information Science, Special Issue on Space-Time Research in GIScience. Taylor & Francis. Link
  • Janowicz, K., Bröring, A., Stasch, C., Schade, S., Everding, T., & Llaves, A. (2011): “A RESTful Proxy and Data Model for Linked Sensor Data”. International Journal of Digital Earth. Taylor & Francis. PDF

Book Chapters

  • Llaves, A., & Everding, T. (2012): “Discovering Geosensor Data by means of an Event Abstraction Layer”. In L. Díaz, C. Granell, & J. Huerta (Eds.), Discovery of Geospatial Resources: Methodologies, Technologies, and Emergent Applications (pp. 112-132). doi:10.4018/978-1-4666-0945-7.ch006. IGI Global. Link

Edited Proceedings

  • Devaraju, A., Llaves, A., Maué, P., & Keßler, C. (eds.) Proceedings of the Workshop Towards Digital Earth: Search, Discover and Share Geospatial Data at Future Internet Symposium. Volume 640 of, ISSN 1613-0073. Berlin, Germany, September 2010. Link

Conference and Workshop Publications

  • Fernández, J. D., Llaves, A., & Corcho, O. (2014): “Efficient RDF Interchange (ERI) Format for RDF Data Streams”. P. Mika et al. (Eds.) ISWC 2014, Part II, LNCS 8797, pp. 244-259, 2014. Springer International Publishing Switzerland. PDF
  • Llaves, A., Fernández, J. D., & Corcho, O. (2014): “Towards Efficient Processing of RDF Data Streams”. 3rd International Workshop on Ordering and Reasoning (OrdRing 2014), held at International Semantic Web Conference 2014 (ISWC 2014). CEUR.
  • Roman, D., Tertre, F., Llaves, A., Grcar, M., Skrjanc, M., Toma, I., Pantazoglou, M., Trasca, S., Bodsberg, N. R., & Borrebæk, M. (2013): “Enabling Access to Environmental Models, Data, and Services on the Web – Technical Results Summary from the ENVISION Project”. Proceedings of the Environmental Information Systems and Services – Infrastructures and Platforms workshop (ENVIP’2013). CEUR. PDF
  • Larizgoitia, I., Toma, I., Beltran, A., Llaves, A., & Maué, P. (2013): “Environmental service discovery based on semantically annotated OGC service descriptions”. In Proceedings of the 28th Annual ACM Symposium on Applied Computing (SAC ’13). ACM, New York, NY, USA, 303-310. Link
  • Llaves, A., Michels, H., Maué, P., & Roth, M. (2012): “Semantic Event Processing in ENVISION”. In Proceedings of the 2nd International Conference on Web Intelligence, Mining and Semantics (WIMS’12). ACM, New York, NY, USA. Link
  • Stasch, C., Schade, S., Llaves, A., Janowicz, K., & Bröring, A. (2011): “Aggregating Linked Sensor Data”. In Kerry Taylor, Arun Ayyagari, David De Roure (Eds.): The 4th International Workshop on Semantic Sensor Networks 2011 (SSN11) in conjunction with the 10th International Semantic Web Conference (ISWC 2011), Bonn, Germany. PDF
  • Llaves, A. (2011): Integration of Geosensor Data by means of an Event Abstraction Layer. In Doctoral Colloquium at Conference on Spatial Information Theory (COSIT’11). Belfast, Maine, USA. PDF
  • Llaves A. (2011): “A Theory for Event Processing of Geosensor Data”. In Proceedings of AGILE Workshop Integrating Sensor Web and Web-based Geoprocessing (ISW). April 2011, Utrecht, The Netherlands. PDF
  • Maué, P., Llaves, A., & Fechner, T. (2010): “Context-aware access to ontologies on the Web”. In Proceedings of Workshop on Ontology Repositories and Editors for the Semantic Web (ORES 2010). 7th Extended Semantic Web Conference (ESWC2010), Heraklion, Crete, Greece. PDF
  • Díaz, L., Gould, M., Beltrán, A., Llaves, A., & Granell, C. (2008): “Multipurpose metadata management in gvSIG”. Academic Proceedings of the 2008 Free and Open Source Software for Geospatial Conference (FOSS4G), pp. 90-99, ISBN 978-0-620-42117-1. September 2008, Cape Town, South Africa. PDF
  • Díaz, L., Granell, C., Beltrán, A., Llaves, A., & Gould, M. (2008): “Extracción automática de metadatos: hacia los metadatos implícitos”. In Actas de las II Jornadas de SIG Libre. Girona, Spain. PDF

Demo Papers

  • Bröring, A., Janowicz, K., Stasch, C., Schade, S., Everding, T., & Llaves, A. (2011): “A RESTful SOS Proxy for Linked Data – Demonstration Paper”. In Kerry Taylor, Arun Ayyagari, David De Roure (Eds.): The 4th International Workshop on Semantic Sensor Networks 2011 (SSN11) in conjunction with the 10th International Semantic Web Conference (ISWC 2011), Bonn, Germany. PDF


  • Llaves, A., & Renschler, C. (2012): “Observing Changes in Real-Time Sensor Observations”. AGILE’2012, 15th International Conference on Geographic Information Science. April 2012, Avignon, France. PDF

Program committee / Paper reviews

  • Semantic Web Journal (2014)
  • International Semantic Web Conference – Replication, Benchmark, Data and Software track (2014)
  • International Workshop on Ordering and Reasoning (OrdRing 2014)
  • RuleML Challenge – International Web Rule Symposium (2013 & 2014)
  • International Journal of Digital Earth (2012)

Edited Reports

  • Dunja Mladeni? et al. (2011): “ENVISION Deliverable 4.2 – Model annotation components and guidelines”, 1-99. PDF
  • Alexandra Moraru et al. (2011): “ENVISION Deliverable 4.3 – Ontologies and Annotations for Environmental Models, and Guidelines for Ontology Maintenance”, 1-62. PDF
  • Alejandro Llaves, and Henry Michels (2012): “ENVISION Deliverable 4.7 – Event Processing of Observation Data”, 1-51. PDF


Supervised Theses

  • Karthikeyan Bollu Ganesh (advisor; MSc thesis, 2011): “An Explorative Interface for Events”.


  • “Map4RDF-iOS: a tool for exploring Linked Geospatial Data”. W3C Workshop on Linking Geospatial Data. March 2014, London, UK.
  • “ENVISION – Environmental Services Infrastructure with Ontologies”. EuroGEOSS 2012 Conference. January 2012, Madrid, Spain.
  • “Geographic Feature Pipes”. Geosemantics DWG session – OGC TC/PC meeting. June 2011, Taichung, Taiwan.
  • “Annotation of Environmental Models in the Envision Project”. Geosemantics DWG session – OGC TC/PC meeting. March 2011, Bonn, Germany.
  • “Open Environmental Services Infrastructure”. Free and Open Source Software for Geospatial (FOSS4G) 2010. September 2010, Barcelona, Spain.
  • “Semantic portals for environmental decision support”. Decision Support DWG session – OGC TC/PC meeting. March 2010, Frascati, Italy

Summer Schools and Courses

  • Vespucci Summer Institute on Spatial Information in Science and Society. Florence, Italy. July 1-7, 2012.
  • Course on Integrated Environmental Management (GEO470/570 IEM). University at Buffalo, NY. August-December, 2011.
  • Course on Geospatial Data Mining (eLearning). School of Statistics and Information Management, New University of Lisbon (ISEGI-NOVA). April-June, 2010.
  • Ifgi Spring School. Topics: Ontology, vagueness and geography; Similarity in Spatial Sciences; Self-organizing maps. Institute for Geoinformatics, University of Münster. March 21-31, 2010.
  • Course on Geographic Information Standards (eLearning). University of the Bundeswehr Munich. November-December, 2008.