October 2012 Volume 15 Number 4 - Educational Technology ...

Conclusions
An approach for the extraction and the annotation of the LO categories of the Universia digital library has been
presented. This approach improves the current solutions of the state of the art because (i) it supports the automatic
selection of the most suitable categories ranked according to its relevance to the LO; and (ii) it is a cross-domain
approach that looks for the solution in more than 700,000 categories of DBpedia. Furthermore, this approach can be
easily extended to manage other linked data repositories different from DBpedia since the filtering algorithm
explores the RDF graph independently of concrete relations of the DBpedia ontology. In fact, it only depends on the
SKOS vocabulary.
Finally, the Universia repository has been transformed in a semantic LO repository following the principles of linked
data. Thus, LO metadata can be directly accessed through a URI and retrieved by means of both a SPARQL
endpoint, that answer semantic queries, and a service lookup, that solves keyword-based queries.
Acknowledgements
This work was supported by the Ministerio de Economía y Competitividad, and the Xunta de Galicia under the
projects TIN2011-22935, and 09SIN065E, respectively.
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