A Span-Based Model for Joint Overlapped and Discontinuous Named Entity Recognition

Fei Li, ZhiChao Lin, Meishan Zhang, Donghong Ji


Abstract
Research on overlapped and discontinuous named entity recognition (NER) has received increasing attention. The majority of previous work focuses on either overlapped or discontinuous entities. In this paper, we propose a novel span-based model that can recognize both overlapped and discontinuous entities jointly. The model includes two major steps. First, entity fragments are recognized by traversing over all possible text spans, thus, overlapped entities can be recognized. Second, we perform relation classification to judge whether a given pair of entity fragments to be overlapping or succession. In this way, we can recognize not only discontinuous entities, and meanwhile doubly check the overlapped entities. As a whole, our model can be regarded as a relation extraction paradigm essentially. Experimental results on multiple benchmark datasets (i.e., CLEF, GENIA and ACE05) show that our model is highly competitive for overlapped and discontinuous NER.
Anthology ID:
2021.acl-long.372
Volume:
Proceedings of the 59th Annual Meeting of the Association for Computational Linguistics and the 11th International Joint Conference on Natural Language Processing (Volume 1: Long Papers)
Month:
August
Year:
2021
Address:
Online
Venues:
ACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
4814–4828
Language:
URL:
https://aclanthology.org/2021.acl-long.372
DOI:
10.18653/v1/2021.acl-long.372
Bibkey:
Cite (ACL):
Fei Li, ZhiChao Lin, Meishan Zhang, and Donghong Ji. 2021. A Span-Based Model for Joint Overlapped and Discontinuous Named Entity Recognition. In Proceedings of the 59th Annual Meeting of the Association for Computational Linguistics and the 11th International Joint Conference on Natural Language Processing (Volume 1: Long Papers), pages 4814–4828, Online. Association for Computational Linguistics.
Cite (Informal):
A Span-Based Model for Joint Overlapped and Discontinuous Named Entity Recognition (Li et al., ACL 2021)
Copy Citation:
PDF:
https://aclanthology.org/2021.acl-long.372.pdf
Video:
 https://aclanthology.org/2021.acl-long.372.mp4
Code
 foxlf823/sodner
Data
GENIA