NAIST QA System for QAC2

The system we presented for the subtask1 and subtask2 in QAC2 is based on our previous one [12], which utilized a greedy answer seeking model using paraphrasing. We incorporate a re-ranking model for matching questions and passages into the previous system. In the model, we integrated a proximitybased scoring function with the structural-based scoring function. Unfortunately, the result of evaluation shows that our proposed model did not work well. Based on error analysis, we conclude that structural matching-based approaches to answer seeking require technologies for large-scale acquisition of paraphrase patterns. We are now investigating a variation of paraphrasing which is expected to be helpful for question answering.