PhD position / Sujet de thèse

Ontology alignment and data interlinking evolution on the web of data

The linked data initiative aims at publishing structured and interlinked data at web scale by using semantic web technologies [1]. These technologies provide different languages for expressing data as graphs (RDF), describing its organization through ontologies (OWL) and querying it (SPARQL) [2].

Linked data facilitates the implementation of applications that reuse data distributed on the web. Until now, the access to data on the web relies on limited Web APIs which provide proprietary interfaces and data formats. Programmers have then to build custom solution for each data source [3].

To facilitates interoperability between application, data issued by different providers has to be interlinked, i.e., the same entity in different data sets must be identified. However, in a heterogeneous system such as the web, there is no reason that two organizations (or providers) make use of the same ontologies to express their data or use the same key to identify entities.

One of the key challenge of linked data is to be able to deal with this heterogeneity by discovering links across datasets [4], but also alignments between ontologies. Until now these two problems have been mainly studied separately, even if some linking approaches take advantage of alignments and ontology matching methods uses common instances to compare concept extensions.

In such a dynamic environment as the web, ontologies and data evolve, and then ontology alignments and links between data have to evolve too. Since alignments and links should not be recomputed each time a change occurs, the semantic web needs methods that consider the evolution.

The goal of this PhD is to study how to evolve alignments and links when ontologies and data change. The followed approach will have to consider the dependency between ontology alignments and links between data. With such an approach, it will be for instance possible to induce new correspondences between ontology entities by using new links and/or decide that some correspondences are not valid anymore. Respectively, adding or removing correspondences will helps to validate (or invalidate) links between instances by using the semantics of alignments.

Given the increasing size of datasets, another important aspect of the work is to enable the scalability of the methods and tools by designing efficient pruning and/or segmentation strategies.

The successful candidate is expected to consider these problems under their theoretical and experimental aspects.


Références:
[1] Christian Bizer, Tom Heath and Tim Berners-Lee (2009). Linked Data - The Story So Far. Int. J. Semantic Web Inf. Syst., 5(3), 1-22.
[2] Pascal Hitzler, Markus Krötzsch, Sebastian Rudolph (2009). Foundations of semantic web technologies, Chapman & Hall/CRC.
[3] Tom Heath and Christian Bizer (2011). Linked Data: Evolving the Web into a Global Data Space. Synthesis Lectures on the Semantic Web: Theory and Technology. Morgan & Claypool.
[4] Alfio Ferrara, Andriy Nikolov and Fran├žois Scharffe (2011). Data Linking for the Semantic Web. Int. J. Semantic Web Inf. Syst., 7(3), 46-76.
[5] Jérôme Euzenat, Pavel Shvaiko (2007). Ontology matching, Springer-Verlag, Heildelberg (DE).


Qualification: Master or equivalent in computer science.

Researched skills:

Environnement: The doctoral work is to be carried out in the Exmo team, a reputed team within the semantic web research area and particularly on ontology matching. We are in contact with the most important teams in France and Europe on these topics.

Doctoral school: Doctoral school MSTII, Université de Grenoble.

Advisor: Jérôme David (Jerome:David#inria:fr) & Jérôme Euzenat (Jerome:Euzenat#inria:fr)

Group: Exmo, INRIA & LIG

Hiring date: October 2013 (negociable).

Place of work: The position is located at INRIA Grenoble Rhône-Alpes, Montbonnot (near Grenoble, France) a main computer science research lab, in a stimulating research environment. Research will be carried out in the Exmo team under the supervision of Jérôme David and Jérôme Euzenat. It will require the involvement of the candidate in related projects.

Duration: 36 months

Salary: 1596 EUR/month net (including full health insurance and social benefits, 1957 EUR gross) upgraded to 1676 EUR/month the 3rd year.

Contact: For further information, contact Jerome:David#inria:fr.

Procedure: Contact us.

File: Provide Vitæ, motivation letter and references.


http://exmo.inria.fr/training/Th-2013-evolution.html

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