The ditlab team participated in the Transfer task composed of dense retrieval and dense reranking subtasks. We trained sentence-BERT by using a Japanese version of mMARCO dataset and commonly used for both subtasks. We compared three types of models that were trained according to three types of losses: softmax, triplet, multiple negatives ranking losses. The results show that the multiple negatives ranking loss was the best for both subtasks. In addition, system fusions significantly improved the performance especially for the retrieval task.
Yuuki Tachioka (Tue,) studied this question.