Bridging the Gap between Decision and Logits in Decision-based Knowledge Distillation for Pre-trained Language Models

Qinhong Zhou, Zonghan Yang, Peng Li, Yang Liu


Abstract
Conventional knowledge distillation (KD) methods require access to the internal information of teachers, e.g., logits. However, such information may not always be accessible for large pre-trained language models (PLMs). In this work, we focus on decision-based KD for PLMs, where only teacher decisions (i.e., top-1 labels) are accessible. Considering the information gap between logits and decisions, we propose a novel method to estimate logits from the decision distributions. Specifically, decision distributions can be both derived as a function of logits theoretically and estimated with test-time data augmentation empirically. By combining the theoretical and empirical estimations of the decision distributions together, the estimation of logits can be successfully reduced to a simple root-finding problem. Extensive experiments show that our method significantly outperforms strong baselines on both natural language understanding and machine reading comprehension datasets.
Anthology ID:
2023.acl-long.738
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:
13234–13248
Language:
URL:
https://aclanthology.org/2023.acl-long.738
DOI:
10.18653/v1/2023.acl-long.738
Bibkey:
Cite (ACL):
Qinhong Zhou, Zonghan Yang, Peng Li, and Yang Liu. 2023. Bridging the Gap between Decision and Logits in Decision-based Knowledge Distillation for Pre-trained Language Models. In Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 13234–13248, Toronto, Canada. Association for Computational Linguistics.
Cite (Informal):
Bridging the Gap between Decision and Logits in Decision-based Knowledge Distillation for Pre-trained Language Models (Zhou et al., ACL 2023)
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PDF:
https://aclanthology.org/2023.acl-long.738.pdf
Video:
 https://aclanthology.org/2023.acl-long.738.mp4