Answering SPARQL Queries using Views

Date(s) - 13/05/2016
10:00 am - 11:00 am



The Semantic Web allows data publishers to make available an increasing number of datasets concerning the whole society. SPARQL queries can be written to consume the datasets data. In this context, the effective execution of SPARQL queries on the relevant datasets is a critical issue. Unfortunately, SPARQL does not allow to access data from the Deep Web, and this significantly reduces the search space. In addition, the existing infrastructures to execute the SPARQL queries do not provide good data availability. To address these two problems, we have used views in the Semantic Web context to optimize the query execution and also the access to the Deep Web. SemLAV is a mediator that allows for executing SPARQL queries over data sources on the Web. SemLAV is based on views that relate external data to the mediator global schema. SemLAV avoids generating and executing an exponential number of query rewritings by computing the materialization order for the selected views. FEDRA considers a federation of SPARQL endpoints that have partially replicated datasets. FEDRA optimizes the execution of federated queries by selecting the endpoints in a way that the transferred data are minimized.


Speaker: Gabriela Montoya

Gabriela Montoya is a researcher in the Distributed Data Management team (GDD)[1], at the Laboratory of Informatics of Nantes Atlantique (LINA)[2] in France, where she did her PhD from October 2012 until March 2016. She has recently defended her thesis titled “Answering SPARQL Queries using Views”, the thesis has been supervised by Prof. Pascal Molli. She works on processing federated queries against federations of sources, with focus on  source selection and query decomposition. Before working at LINA, she was Lecturer in the Computer Science Department at the Universidad Simón Bolívar (Venezuela), where she has taught Logic, Algorithms and Programming Languages courses and labs at undergraduate level. She obtained her Master and Bachelor degrees from the Universidad Simón Bolívar in 2006 and 2009 respectively.
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