IRn in the CLEF Robust WSD Task 2008

This paper describes our participation in the Robust WSD Task within the CLEF 2008. The aim of this pilot task is exploring methods which can take profit of WSD in-formation in order to improve the IR systems. In our approach we have used a passage based system jointly with a WordNet based expansion method for the collection docu-ments and the queries using the two WSD systems runs provided by the organization. Furthermore we have experimented with two well known relevance feedback methods- LCA and PRF-, in order to figure out which is more suitable to take profit of the WSD query expansion based on Wordnet. Our best run has obtained a 4th place in the competition with a value of 0.4008 MAP. We conclude that LCA fits better than PRF to this task. And that our WSD expansion is useful for some query subsets. In future works we will study the features of the query subsets for which the performance of our system decreases