david-eichmann(Puiowa.edu mruizQcs.uiowa.edu Abstract We investigate an automatic method for Cross Language Information Retrieval (CLIR) that uti-lizes the multilingual UMLS Metathesaurus to translate Spanish and French natural language queries into En-glish. Two experiments are presented using OHSUMED, a subset of MEDLINE. Both experiments examine re-trieval effectiveness of the translated queries. However, in the second experiment, the query translation procedure is augmented with digram based vocabulary normaliza-tion procedures. In this comparative study of retrieval effectiveness the measures used are: 11-point-average precision score (11-AvgP); average interpolated preci-sion at recall of 0.1; and noninterpolated (i.e., exact) precision after 10 retrieved documents. Our results in-dicate that for Spanish the UMLS Metathesaurus based CLIR method appears equivalent to multilingual dictio-nary based approaches investigated in the current litera-ture French yields less favorable results and our analysis suggests that linguistic differences may have caused the performance differences. 1

Introduction Cross-Language Information Retrieval (CLIR) was a new task in the TREC-6 evaluation. In contrast to the multilingual track included in previous TREC evaluations, which was concerned with information retrieval in Spanish or Chinese, the cross-language retrieval track focuses on the retrieval situation where the documents are written in a language which is different than the language used to specify the queries. The TREC-6 track used documents in English, French and German and queries in English, French, German, Spanish and Dutch. There are many applications or scenarios in which a user of a retrieval system may be interested in finding information written in a language other than the user's native or preferred language. In some applications, a user may want to discover all possible relevant information in a multilingual textbase, irrespective of the language of the relevant information. This may be the case when searc

Cross-Language Information Retrieval (CLIR) systems enable users to formulate queries in their native language to retrieve documents in foreign languages. Because queries and documents in CLIR do not necessarily share the same language, translation is needed before matching can take place. This translation step tends to cause a reduction in the retrieval performance of CLIR as compared to monolingual information retrieval. The prevailing CLIR approach and the focus of this study is query translation. The translation of queries is inherently difficult due to the lack of a one-to-one mapping of a lexical item and its meaning, which creates lexical ambiguity. This, and other translation problems, result in translation errors which impact CLIR performance. To understand the events occurring in cross-language retrieval query translation and the relation of these events to retrieval performance, the study explored the following research questions: 1) What kinds of translation events affect cross-language retrieval? 2) In what way does the presence of certain translation events in query translation affect retrieval performance? The study followed a two-phase multi-method approach. In phase one, a taxonomy of translation events was created through content analysis of queries and their translations in combination with an examination of the literature. In the second and final phase, a subset of the test queries was coded using the taxonomy resulting from phase one. These queries were then used in information retrieval experimentation to assess the impact of the translation events on retrieval performance.

With the globalization of the world markets, the need for multilingual information processing