A Boundary-aware Neural Model for Nested Named Entity Recognition

Changmeng Zheng, Yi Cai, Jingyun Xu, Ho-fung Leung, Guandong Xu

Abstract
In natural language processing, it is common that many entities contain other entities inside them. Most existing works on named entity recognition (NER) only deal with flat entities but ignore nested ones. We propose a boundary-aware neural model for nested NER which leverages entity boundaries to predict entity categorical labels. Our model can locate entities precisely by detecting boundaries using sequence labeling models. Based on the detected boundaries, our model utilizes the boundary-relevant regions to predict entity categorical labels, which can decrease computation cost and relieve error propagation problem in layered sequence labeling model. We introduce multitask learning to capture the dependencies of entity boundaries and their categorical labels, which helps to improve the performance of identifying entities. We conduct our experiments on GENIA dataset and the experimental results demonstrate that our model outperforms other state-of-the-art methods.
Anthology ID:
D19-1034
Volume:
Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP)
Month:
November
Year:
2019
Address:
Hong Kong, China
Venues:
EMNLP | IJCNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
357–366
Language:
URL:
https://aclanthology.org/D19-1034
DOI:
10.18653/v1/D19-1034
Bibkey:
Cite (ACL):
Changmeng Zheng, Yi Cai, Jingyun Xu, Ho-fung Leung, and Guandong Xu. 2019. A Boundary-aware Neural Model for Nested Named Entity Recognition. In Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP), pages 357–366, Hong Kong, China. Association for Computational Linguistics.
Cite (Informal):
A Boundary-aware Neural Model for Nested Named Entity Recognition (Zheng et al., EMNLP-IJCNLP 2019)
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PDF:
https://preview.aclanthology.org/ingestion-script-update/D19-1034.pdf
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 D19-1034.Attachment.zip
Data
GENIA
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