SpanNER: Named Entity Re-/Recognition as Span Prediction

Jinlan Fu, Xuanjing Huang, Pengfei Liu


Abstract
Recent years have seen the paradigm shift of Named Entity Recognition (NER) systems from sequence labeling to span prediction. Despite its preliminary effectiveness, the span prediction model’s architectural bias has not been fully understood. In this paper, we first investigate the strengths and weaknesses when the span prediction model is used for named entity recognition compared with the sequence labeling framework and how to further improve it, which motivates us to make complementary advantages of systems based on different paradigms. We then reveal that span prediction, simultaneously, can serve as a system combiner to re-recognize named entities from different systems’ outputs. We experimentally implement 154 systems on 11 datasets, covering three languages, comprehensive results show the effectiveness of span prediction models that both serve as base NER systems and system combiners. We make all codes and datasets available: https://github.com/neulab/spanner, as well as an online system demo: http://spanner.sh. Our model also has been deployed into the ExplainaBoard platform, which allows users to flexibly perform a system combination of top-scoring systems in an interactive way: http://explainaboard.nlpedia.ai/leaderboard/task-ner/.
Anthology ID:
2021.acl-long.558
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
Editors:
Chengqing Zong, Fei Xia, Wenjie Li, Roberto Navigli
Venues:
ACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
7183–7195
Language:
URL:
https://aclanthology.org/2021.acl-long.558
DOI:
10.18653/v1/2021.acl-long.558
Bibkey:
Cite (ACL):
Jinlan Fu, Xuanjing Huang, and Pengfei Liu. 2021. SpanNER: Named Entity Re-/Recognition as Span Prediction. 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 7183–7195, Online. Association for Computational Linguistics.
Cite (Informal):
SpanNER: Named Entity Re-/Recognition as Span Prediction (Fu et al., ACL-IJCNLP 2021)
Copy Citation:
PDF:
https://aclanthology.org/2021.acl-long.558.pdf
Video:
 https://aclanthology.org/2021.acl-long.558.mp4
Code
 neulab/spanner
Data
CoNLL 2002WNUT 2016 NERWNUT 2017