EDIS: Diagnosing LLM Reasoning via Entropy Dynamics

Fuente: arXiv
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Main Authors: Zhu, Chenghua, Wu, Siyan, Zeng, Xiangkang, Xu, Zishan, Kang, Zhaolu, Guo, Yifu, Lu, Yuquan, Huang, Junduan, Zhou, Guojing
Format: Preprint
Published: 2026
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author Zhu, Chenghua
Wu, Siyan
Zeng, Xiangkang
Xu, Zishan
Kang, Zhaolu
Guo, Yifu
Lu, Yuquan
Huang, Junduan
Zhou, Guojing
author_facet Zhu, Chenghua
Wu, Siyan
Zeng, Xiangkang
Xu, Zishan
Kang, Zhaolu
Guo, Yifu
Lu, Yuquan
Huang, Junduan
Zhou, Guojing
contents Entropy-based confidence signals are increasingly leveraged to improve reasoning in large language models (LLMs), yet existing approaches treat confidence as a static quantity -- typically aggregated over tokens. We show that the \emph{temporal evolution} of confidence during generation carries richer information than aggregate statistics alone. Analyzing token-level entropy trajectories, we identify characteristic patterns distinguishing correct from incorrect reasoning: erroneous solutions exhibit unstable dynamics, including burst spikes (sustained uncertainty growth) and peak-valley spikes (sharp rebounds following transient confidence). These patterns persist across models and training stages, suggesting they reflect intrinsic properties of reasoning failure rather than superficial noise. To formalize this observation, we introduce the Entropy Dynamics Instability Score (\textbf{EDIS}), a trajectory-level metric quantifying instability in entropy evolution. EDIS serves as an effective diagnostic signal for inference-time selection, substantially improving reasoning accuracy, and offers a promising direction for training-time sample curation. Our findings establish entropy dynamics as an underexplored yet informative lens for understanding and improving LLM reasoning.
format Preprint
id arxiv_https___arxiv_org_abs_2602_01288
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle EDIS: Diagnosing LLM Reasoning via Entropy Dynamics
Zhu, Chenghua
Wu, Siyan
Zeng, Xiangkang
Xu, Zishan
Kang, Zhaolu
Guo, Yifu
Lu, Yuquan
Huang, Junduan
Zhou, Guojing
Machine Learning
Entropy-based confidence signals are increasingly leveraged to improve reasoning in large language models (LLMs), yet existing approaches treat confidence as a static quantity -- typically aggregated over tokens. We show that the \emph{temporal evolution} of confidence during generation carries richer information than aggregate statistics alone. Analyzing token-level entropy trajectories, we identify characteristic patterns distinguishing correct from incorrect reasoning: erroneous solutions exhibit unstable dynamics, including burst spikes (sustained uncertainty growth) and peak-valley spikes (sharp rebounds following transient confidence). These patterns persist across models and training stages, suggesting they reflect intrinsic properties of reasoning failure rather than superficial noise. To formalize this observation, we introduce the Entropy Dynamics Instability Score (\textbf{EDIS}), a trajectory-level metric quantifying instability in entropy evolution. EDIS serves as an effective diagnostic signal for inference-time selection, substantially improving reasoning accuracy, and offers a promising direction for training-time sample curation. Our findings establish entropy dynamics as an underexplored yet informative lens for understanding and improving LLM reasoning.
title EDIS: Diagnosing LLM Reasoning via Entropy Dynamics
topic Machine Learning
url https://arxiv.org/abs/2602.01288