Wednesday, July 16, 2014

New DBpedia Graph Statistics

Recently, we have been working on the DBpedia / Wikipedia Page Link dataset. We have considered the English and the German language versions for this project. In the current DBpedia 3.9 page links English and German datasets 18 million and 6 million entities are represented respectively. But the original DBpedia only contains about 4 million and 1 million distinct entities for English and German versions. This significant difference is mainly due to the current DBpedia pagelinks dataset include redirect pages and pagelinks with resources that are not considered as entites (as e.g. thumbnails and other images). So we considered cleaning up DBpedia pagelinks dataset for the computation of statistical parameters (a.g. pagerank or HITS). For the Cleanup we have removed all unnecessary and redundant RDF-Triples from the pagelinks dataset, i.e all removing the redirect pages (Redirection pages are just URIs that automatically forward a user to another Wikipedia page, but do not represent entities) as well as RDF-Triples representing resources that do not have an own rdfs:label (as per DBpedia documentation every entity has an rdfs:label reference).

One of the benefits of the cleaned up pagelink dataset is the faster computation of statistical graph measures (while not influencing the overall statistics, i.e. redirect pages usually don't have incoming links and theother removed resources (as e.g. images) don't have outgoing links). Based on this dataset we have computed PageRank, Hub and Authorities (HITS), PageInlink Counts and PageOutLink Counts. Please find the details of the datasets here on our research group's webpage [1].

For Computation of the DBpedia graph statistics we have used JUNG — the Java Universal Network/Graph Framework. Please find the source code for PageRank and HITS computation here via GitHub [2].

References and further Reading:
[1] New PageRank Computations for DBpedia 3.9 (English/German) at SemanticMultimedia
[2] Source code for DBpedia Graph Statistics

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