Document Expansion for Cross-Lingual Passage Retrieval

This article describes the participation of the joint Elhuyar-IXA group in the ResPubliQA exercise at QA&CLEF 2010. In particular, we participated in the English–English monolingual task and in the Basque– English cross-lingual one. Our focus was threefold: (1) to check to what extent information retrieval (IR) can achieve good results in passage retrieval without question analysis and answer validation, (2) to check dictionary techniques for Basque to English retrieval when faced with the lack of parallel corpora for Basque in this domain, and (3) to check the contribution of semantic relatedness based on WordNet to expand the passages to related words. Our results show that IR provides good results in the monolingual task, that our performance drop in the cross-lingual system was much greater than in previous CLIR experiments, and that expansion improves the results in the monolingual task.