Continual Contrastive Finetuning Improves Low-Resource Relation Extraction

Wenxuan Zhou, Sheng Zhang, Tristan Naumann, Muhao Chen, Hoifung Poon


Abstract
Relation extraction (RE), which has relied on structurally annotated corpora for model training, has been particularly challenging in low-resource scenarios and domains. Recent literature has tackled low-resource RE by self-supervised learning, where the solution involves pretraining the entity pair embedding by RE-based objective and finetuning on labeled data by classification-based objective. However, a critical challenge to this approach is the gap in objectives, which prevents the RE model from fully utilizing the knowledge in pretrained representations. In this paper, we aim at bridging the gap and propose to pretrain and finetune the RE model using consistent objectives of contrastive learning. Since in this kind of representation learning paradigm, one relation may easily form multiple clusters in the representation space, we further propose a multi-center contrastive loss that allows one relation to form multiple clusters to better align with pretraining. Experiments on two document-level RE datasets, BioRED and Re-DocRED, demonstrate the effectiveness of our method. Particularly, when using 1% end-task training data, our method outperforms PLM-based RE classifier by 10.5% and 6.1% on the two datasets, respectively.
Anthology ID:
2023.acl-long.739
Volume:
Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2023
Address:
Toronto, Canada
Editors:
Anna Rogers, Jordan Boyd-Graber, Naoaki Okazaki
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
13249–13263
Language:
URL:
https://aclanthology.org/2023.acl-long.739
DOI:
10.18653/v1/2023.acl-long.739
Bibkey:
Cite (ACL):
Wenxuan Zhou, Sheng Zhang, Tristan Naumann, Muhao Chen, and Hoifung Poon. 2023. Continual Contrastive Finetuning Improves Low-Resource Relation Extraction. In Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 13249–13263, Toronto, Canada. Association for Computational Linguistics.
Cite (Informal):
Continual Contrastive Finetuning Improves Low-Resource Relation Extraction (Zhou et al., ACL 2023)
Copy Citation:
PDF:
https://aclanthology.org/2023.acl-long.739.pdf
Video:
 https://aclanthology.org/2023.acl-long.739.mp4