Thomson Legal and Regulatory at NTCIR-4: Monolingual and Pivot-Language Retrieval Experiments

Thomson Legal and Regulatory participated in the CLIR task of the NTCIR-4 workshop. We submitted formal runs for monolingual retrieval in Japanese, Chinese and Korean. Our bilingual runs from Chinese and Korean to Japanese rely on English as a pivot language. During our monolingual experiments, we compared building stopword lists using query logs to building stopword lists from collection statistics with further manual editing. We investigated decompounding for Korean, more precisely partial credit of compound parts. Finally we incorporated pseudo-relevance feedback in our Japanese runs. Our bilingual approach was an experiment to construct a system within a short timeframe using publically available resources. The low quality of retrieval suggests that such an approach is not viable in a real environment.