Toshiba participated in the Monolingual/Bilingual tasks at NTCIR-4 CLIR using our CLIR system called BRIDJE. We submitted 24 runs covering three topic languages (Japanese, English and Chinese) and two document languages (Japanese and English) and achieved the highest performances in the E-J-D, CJ-D, C-J-T, E-E-D, J-E-D, J-E-T subtasks. We had 12 more runs which we were not allowed to submit due to the limitation on the number of runs, with which we would have achieved the highest performances in the J-J-D, C-E-D and C-E-T subtasks as well. Based on our formal run results, this paper discusses (a) the feasibility of the MT-based pivot language approach; (b) the effectiveness of our new Flexible Pseudo-Relevance Feedback methods; and (c) the advantages of Q-measure, which is a new retrieval performance metric based on multigrade relevance.
['Tetsuya Sakai', 'Makoto Koyama', 'Akira Kumano', 'Toshihiko Manabe']
Toshiba BRIDJE at NTCIR-4 CLIR: Monolingual/Bilingual IR and Flexible Feedback