Michael Glass
2020
Span Selection Pre-training for Question Answering
Michael Glass
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Alfio Gliozzo
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Rishav Chakravarti
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Anthony Ferritto
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Lin Pan
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G P Shrivatsa Bhargav
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Dinesh Garg
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Avi Sil
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics
BERT (Bidirectional Encoder Representations from Transformers) and related pre-trained Transformers have provided large gains across many language understanding tasks, achieving a new state-of-the-art (SOTA). BERT is pretrained on two auxiliary tasks: Masked Language Model and Next Sentence Prediction. In this paper we introduce a new pre-training task inspired by reading comprehension to better align the pre-training from memorization to understanding. Span Selection PreTraining (SSPT) poses cloze-like training instances, but rather than draw the answer from the model’s parameters, it is selected from a relevant passage. We find significant and consistent improvements over both BERT-BASE and BERT-LARGE on multiple Machine Reading Comprehension (MRC) datasets. Specifically, our proposed model has strong empirical evidence as it obtains SOTA results on Natural Questions, a new benchmark MRC dataset, outperforming BERT-LARGE by 3 F1 points on short answer prediction. We also show significant impact in HotpotQA, improving answer prediction F1 by 4 points and supporting fact prediction F1 by 1 point and outperforming the previous best system. Moreover, we show that our pre-training approach is particularly effective when training data is limited, improving the learning curve by a large amount.
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Co-authors
- Alfio Gliozzo 1
- Rishav Chakravarti 1
- Anthony Ferritto 1
- Lin Pan 1
- G P Shrivatsa Bhargav 1
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- ACL1