dexa2017_newDEXA International Conference on Database and Expert Systems Applications – DEXA 2017 is one of the major venues for discussing the latest scientific results and technologies around database, information, and knowledge systems. Our members have actively participated in 28th DEXA 2017 Conferences and Workshops, which took place in Lyon, France from August 28-31, 2017.

e are very pleased to report that:

4 papers from our group were accepted for presentation @DEXA2017

  • MULDER: Querying the Linked Data Web by Bridging RDF Molecule Templates by Kemele M. Endris, Mikhail Galkin, Ioanna Lytra, Mohamed Nadjib Mami, Maria-Esther Vidal and Sören Auer.
    Kemele M. Endris, presented his work on Querying the Linked Data Web by Bridging RDF Molecule Templates in the main conference.

    The audience showed high interest in his presentation and appreciated such a composition into existing query processing engines.
    Kemele M. Endris secured a Best Research Paper Award for his work.

    Abstract. The increasing number of RDF data sources that allow for querying Linked Data via Web services form the basis for federated SPARQL query processing. Federated SPARQL query engines provide a unified view of a federation of RDF data sources, and rely on source descriptions for selecting the data sources over which unified queries will be executed. Albeit efficient, existing federated SPARQL query engines usually ignore the meaning of data accessible from a data source, and describe sources only in terms of the vocabularies utilized in the data source. Lack of source description may conduce to the erroneous selection of data sources for a query, thus affecting the performance of query processing over the federation. We tackle the problem of federated SPARQL query processing and devise MULDER, a query engine for federations of RDF data sources. MULDER describes data sources in terms of RDF molecule templates, i.e., abstract descriptions of entities belonging to the same RDF class. Moreover, MULDER utilizes RDF molecule templates for source selection, and query decomposition and optimization. We empirically study the performance of MULDER on existing benchmarks, and compare MULDER performance with state-of-the-art federated SPARQL query engines. Experimental results suggest that RDF molecule templates empower MULDER federated query processing, and allow for the selection of RDF data sources that not only reduce execution time, but also increase answer completeness.

DEXA2017 was a great venue to meet the community, create new connections, talk about current research challenges, share ideas and settle new collaborations. We look forward to the next DEXA conference.