A Survey on Entropy Mechanism in Large Reasoning Models

Zihan Wang, Xingle Xu, Hao Wang, Yiwen Ye, Yuchen Li, Linhao Wang, Hongze Tan, Peidong Wang, Shi Feng, Guoqing Chen, Jinghao Lin, Zijing Wang, Yiqun Zhang, Yongkang Liu, Xiaocui Yang, Tao Yan, Lei Yang, Shengzhi Wang, Yuhang Wu, Ge Yu


Abstract
Entropy mechanism emerges as a key organizing principle for understanding and improving Large Reasoning Models (LRMs). This survey examines how entropy shapes both their training and inference behavior. On the training side, we take a mathematical perspective: casting existing RL-based reasoning algorithms into a unified objective and using this formulation to derive an entropy-centric decomposition of methods, clarifying how different approaches adjust exploration–exploitation "knobs". On the inference side, based on the characteristic of LRM that trading increased inference tokens yields better performance, we summarize methods that leverage entropy to enhance inference performance or reduce uncertainty. Finally, we discuss open challenges and future directions of entropy-driven research for LRMs. Our repository is available on https://anonymous.4open.science/r/Awesome_LRM_with_Entropy-0503.
Anthology ID:
2026.findings-emnlp.2478
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
53321–53347
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2478/
DOI:
Bibkey:
Cite (ACL):
Zihan Wang, Xingle Xu, Hao Wang, Yiwen Ye, Yuchen Li, Linhao Wang, Hongze Tan, Peidong Wang, Shi Feng, Guoqing Chen, Jinghao Lin, Zijing Wang, Yiqun Zhang, Yongkang Liu, Xiaocui Yang, Tao Yan, Lei Yang, Shengzhi Wang, Yuhang Wu, and Ge Yu. 2026. A Survey on Entropy Mechanism in Large Reasoning Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 53321–53347, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
A Survey on Entropy Mechanism in Large Reasoning Models (Wang et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.2478.pdf