Stochastic Bridges as Effective Regularizers for Parameter-Efficient Tuning

Weize Chen, Xu Han, Yankai Lin, Zhiyuan Liu, Maosong Sun, Jie Zhou


Abstract
Parameter-efficient tuning methods (PETs) have achieved promising results in tuning large pre-trained language models (PLMs). By formalizing frozen PLMs and additional tunable parameters as systems and controls respectively, PETs can be theoretically grounded to optimal control and further viewed as optimizing the terminal cost and running cost in the optimal control literature. Despite the elegance of this theoretical grounding, in practice, existing PETs often ignore the running cost and only optimize the terminal cost, i.e., focus on optimizing the loss function of the output state, regardless of the running cost that depends on the intermediate states. Since it is non-trivial to directly model the intermediate states and design a running cost function, we propose to use latent stochastic bridges to regularize the intermediate states and use the regularization as the running cost of PETs. As the first work to propose regularized PETs that use stochastic bridges as the regularizers (running costs) for the intermediate states, we show the effectiveness and generality of this regularization across different tasks, PLMs and PETs. In view of the great potential and capacity, we believe more sophisticated regularizers can be designed for PETs and better performance can be achieved in the future.
Anthology ID:
2023.findings-acl.661
Volume:
Findings of the Association for Computational Linguistics: ACL 2023
Month:
July
Year:
2023
Address:
Toronto, Canada
Editors:
Anna Rogers, Jordan Boyd-Graber, Naoaki Okazaki
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
10400–10420
Language:
URL:
https://aclanthology.org/2023.findings-acl.661
DOI:
10.18653/v1/2023.findings-acl.661
Bibkey:
Cite (ACL):
Weize Chen, Xu Han, Yankai Lin, Zhiyuan Liu, Maosong Sun, and Jie Zhou. 2023. Stochastic Bridges as Effective Regularizers for Parameter-Efficient Tuning. In Findings of the Association for Computational Linguistics: ACL 2023, pages 10400–10420, Toronto, Canada. Association for Computational Linguistics.
Cite (Informal):
Stochastic Bridges as Effective Regularizers for Parameter-Efficient Tuning (Chen et al., Findings 2023)
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PDF:
https://aclanthology.org/2023.findings-acl.661.pdf