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Main Authors: Zhang, Haoran, Li, Yafu, Wang, Zhi, Wang, Zhilin, Zhang, Shunkai, Qu, Xiaoye, Cheng, Yu
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.08498
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author Zhang, Haoran
Li, Yafu
Wang, Zhi
Wang, Zhilin
Zhang, Shunkai
Qu, Xiaoye
Cheng, Yu
author_facet Zhang, Haoran
Li, Yafu
Wang, Zhi
Wang, Zhilin
Zhang, Shunkai
Qu, Xiaoye
Cheng, Yu
contents Large Reasoning Models (LRMs) increasingly rely on reasoning traces with complex internal structures. However, existing work lacks a unified answer to three fundamental questions: (1) what defines high-quality reasoning, (2) how to reliably evaluate long, implicitly structured reasoning traces, and (3) how to use such evaluation signals for reasoning optimization. To address these challenges, we provide a unified perspective. (1) We introduce the ME$^2$ principle to characterize reasoning quality along macro- and micro-level concerning efficiency and effectiveness. (2) Built on this principle, we model reasoning traces as directed acyclic graphs (DAGs) and develop a DAG-based pairwise evaluation method, capturing complex reasoning structures. (3) Based on this method, we construct the TRM-Preference dataset and train a Thinking Reward Model (TRM) to evaluate reasoning quality at scale. Experiments show that thinking rewards serve as an effective optimization signal. At test time, selecting better reasoning leads to better outcomes (up to 19.3% gain), and during RL training, thinking rewards enhance reasoning and performance (up to 3.9% gain) across diverse tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2602_08498
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Characterizing, Evaluating, and Optimizing Complex Reasoning
Zhang, Haoran
Li, Yafu
Wang, Zhi
Wang, Zhilin
Zhang, Shunkai
Qu, Xiaoye
Cheng, Yu
Computation and Language
Large Reasoning Models (LRMs) increasingly rely on reasoning traces with complex internal structures. However, existing work lacks a unified answer to three fundamental questions: (1) what defines high-quality reasoning, (2) how to reliably evaluate long, implicitly structured reasoning traces, and (3) how to use such evaluation signals for reasoning optimization. To address these challenges, we provide a unified perspective. (1) We introduce the ME$^2$ principle to characterize reasoning quality along macro- and micro-level concerning efficiency and effectiveness. (2) Built on this principle, we model reasoning traces as directed acyclic graphs (DAGs) and develop a DAG-based pairwise evaluation method, capturing complex reasoning structures. (3) Based on this method, we construct the TRM-Preference dataset and train a Thinking Reward Model (TRM) to evaluate reasoning quality at scale. Experiments show that thinking rewards serve as an effective optimization signal. At test time, selecting better reasoning leads to better outcomes (up to 19.3% gain), and during RL training, thinking rewards enhance reasoning and performance (up to 3.9% gain) across diverse tasks.
title Characterizing, Evaluating, and Optimizing Complex Reasoning
topic Computation and Language
url https://arxiv.org/abs/2602.08498