Better, Faster, Stronger Sequence Tagging Constituent Parsers
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- OA-Better, Faster, Stronger Sequence Tagging Constituent Parsers
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Sequence tagging models for constituent parsing are faster, but less accurate than other types of parsers. In this work, we address the following weaknesses of such constituent parsers: (a) high error rates around closing brackets of long constituents, (b) large label sets, leading to sparsity, and (c) error propagation arising from greedy decoding. To effectively close brackets, we train a model that learns to switch between tagging schemes. To reduce sparsity, we decompose the label set and use multi-task learning to jointly learn to predict sublabels. Finally, we mitigate issues from greedy decoding through auxiliary losses and sentence-level fine-tuning with policy gradient. Combining these techniques, we clearly surpass the performance of sequence tagging constituent parsers on the English and Chinese Penn Treebanks, and reduce their parsing time even further. On the SPMRL datasets, we observe even greater improvements across the board, including a new state of the art on Basque, Hebrew, Polish and Swedish.
Original language | English |
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Title of host publication | Proceedings of the 2019 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies, Volume 1 (Long and Short Papers) |
Publisher | Association for Computational Linguistics |
Publication date | 2019 |
Pages | 3372-3383 |
DOIs | |
Publication status | Published - 2019 |
Event | 2019 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies - NAACL-HLT 2019 - Minneapolis, United States Duration: 3 Jun 2019 → 7 Jun 2019 |
Conference
Conference | 2019 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies - NAACL-HLT 2019 |
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Land | United States |
By | Minneapolis |
Periode | 03/06/2019 → 07/06/2019 |
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