Read + Verify: Machine Reading Comprehension with Unanswerable Questions

Machine reading comprehension with unanswerable questions aims to abstain from answering when no answer can be inferred. In addition to extract answers, previous works usually predict an additional “no-answer” probability to detect unanswerable cases. However, they fail to validate the answerability of the question by verifying the legitimacy of the predicted answer. To address this problem, we propose a novel read-then-verify system, which not only utilizes a neural reader to extract candidate answers and produce noanswer probabilities, but also leverages an answer verifier to decide whether the predicted answer is entailed by the input snippets. Moreover, we introduce two auxiliary losses to help the reader better handle answer extraction as well as noanswer detection, and investigate three different architectures for the answer verifier. Our experiments on the SQuAD 2. 0 dataset show that our system obtains a score of 74. 2 F1 on test set, achieving state-of-the-art results at the time of submission (Aug. 28th, 2018).

Authors

• Minghao Hu Information Research Center of Military Science, China
• Furu Wei Microsoft
• Yuxing Peng
• Zhen Huang National University of Defense Technology
• Nan Yang Tianjin University
• Dongsheng Li

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