TNO at CLEF-2001: Comparing Translation Resources

This paper describes the official runs of TNO TPD for CLEF-2001. We participated in the monolingual, bilingual and multilingual tasks. The main contribution of this paper is a systematic comparison of three types of translation resources for bilingual retrieval based on query translation. We compared several techniques based on machine readable dictionaries, statistical dictionaries generated from parallel corpora with a baseline of the Babelfish MT service, which is available on the web. The study showed that the topic set is too small to draw reliable conclusions. All three methods have the potential to reach about 90% of the monolingual baseline performance, but the effectiveness is not consistent across language pairs and topic collections. Because each of the individual methods are quite sensitive to missing translations, we tested a combination approach, which yielded consistent improvements up to 98% of the monolingual baseline.