TREC-9 Cross-Language Information Retrieval (English-Chinese) Overview

(English Chinese) Overview Fredri Gey and Aitao Chen UC DATA and SIMS University of California, Berkeley e-mail: gey u data.berkeley.edu,aitao sims.berkeley.edu Abstra t Sixteen groups parti ipated in the TREC-9 ross-language information retrieval tra k whi h fo ussed on retrieving Chinese language do uments in response to 25 English queries. A variety of CLIR approa hes were tested and a ri h set of experiments performed whi h measured the utility of various resour es su h as ma hine translation and parallel orpora, as well as preand posttranslation query expansion using pseudo-relevan e feedba k. 1 Introdu tion For TREC-9 the ross-language information retrieval task was to utilize English queries against Chinese do uments. This aspe t of multilingual information a ess at TREC-9 was the seventh year in whi h non-English do ument retrieval was tested and evaluated, and the fourth year for whi h ross-language information retrieval has been experimented with. In TREC-3, retrieval of 25 queries against a Mexi an newspaper orpus was tested by four groups. Spanish language retrieval was evaluated in TREC-3, TREC-4 (another 25 queries for the same Mexi an orpus), and TREC-5 (where an European Spanish orpus was used). In TREC-5 a Chinese language tra k was introdu ed using both newspaper (People's Daily) and newswire (XinHua) sour es from People's Republi of China and 25 Chinese queries with an English translation supplied. The TREC-5 orpus was represented with the GB hara ter set for the simpli ed Chinese language of PRC. Chinese monolingual experiments on this olle tion were done in TREC-5 and TREC-6 and sparked serious resear h into Chinese text segmentation methods using di tionary methods as well as statisti al methods using measures su h as mutual information. Comparisons have been made with simple overlapping bigram segmentation methods for monolingual Chinese retrieval. TREC onferen es TREC-6, TREC-7 and TREC-8 has ross language tra ks whi h fo ussed upon European languages (English, Fren h, German, and later Italian). Following TREC-8 the venue for evaluating European language retrieval moved to Europe with the Cross-Language Evaluation Forum (CLEF) rst held in Lisbon in September 2000 [9℄.