GPL: Generative Pseudo Labeling for Unsupervised Domain Adaptation of Dense Retrieval

Kexin Wang, Nandan Thakur, Nils Reimers, Iryna Gurevych


Abstract
Dense retrieval approaches can overcome the lexical gap and lead to significantly improved search results. However, they require large amounts of training data which is not available for most domains. As shown in previous work (Thakur et al., 2021b), the performance of dense retrievers severely degrades under a domain shift. This limits the usage of dense retrieval approaches to only a few domains with large training datasets. In this paper, we propose the novel unsupervised domain adaptation method Generative Pseudo Labeling (GPL), which combines a query generator with pseudo labeling from a cross-encoder. On six representative domain-specialized datasets, we find the proposed GPL can outperform an out-of-the-box state-of-the-art dense retrieval approach by up to 9.3 points nDCG@10. GPL requires less (unlabeled) data from the target domain and is more robust in its training than previous methods. We further investigate the role of six recent pre-training methods in the scenario of domain adaptation for retrieval tasks, where only three could yield improved results. The best approach, TSDAE (Wang et al., 2021) can be combined with GPL, yielding another average improvement of 1.4 points nDCG@10 across the six tasks. The code and the models are available at https://github.com/UKPLab/gpl.
Anthology ID:
2022.naacl-main.168
Volume:
Proceedings of the 2022 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies
Month:
July
Year:
2022
Address:
Seattle, United States
Venue:
NAACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2345–2360
Language:
URL:
https://aclanthology.org/2022.naacl-main.168
DOI:
10.18653/v1/2022.naacl-main.168
Bibkey:
Cite (ACL):
Kexin Wang, Nandan Thakur, Nils Reimers, and Iryna Gurevych. 2022. GPL: Generative Pseudo Labeling for Unsupervised Domain Adaptation of Dense Retrieval. In Proceedings of the 2022 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies, pages 2345–2360, Seattle, United States. Association for Computational Linguistics.
Cite (Informal):
GPL: Generative Pseudo Labeling for Unsupervised Domain Adaptation of Dense Retrieval (Wang et al., NAACL 2022)
Copy Citation:
PDF:
https://aclanthology.org/2022.naacl-main.168.pdf
Software:
 2022.naacl-main.168.software.zip
Code
 ukplab/gpl +  additional community code
Data
BEIRBioASQMS MARCOPAQSciFact