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Main Authors: Tang, Yuntian, Jia, Bohan, Huang, Wenxuan, Zhang, Lianyue, Xie, Jiao, Li, Wenxi, Li, Wei, Hu, Jie, Ji, Xinghao Chen Rongrong, Lin, Shaohui
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.08324
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author Tang, Yuntian
Jia, Bohan
Huang, Wenxuan
Zhang, Lianyue
Xie, Jiao
Li, Wenxi
Li, Wei
Hu, Jie
Ji, Xinghao Chen Rongrong
Lin, Shaohui
author_facet Tang, Yuntian
Jia, Bohan
Huang, Wenxuan
Zhang, Lianyue
Xie, Jiao
Li, Wenxi
Li, Wei
Hu, Jie
Ji, Xinghao Chen Rongrong
Lin, Shaohui
contents Chain-of-Thought (CoT) reasoning successfully enhances the reasoning capabilities of Large Language Models (LLMs), yet it incurs substantial computational overhead for inference. Existing CoT compression methods often suffer from a critical loss of logical fidelity at high compression ratios, resulting in significant performance degradation. To achieve high-fidelity, fast reasoning, we propose a novel EXTreme-RAtio Chain-of-Thought Compression framework, termed Extra-CoT, which aggressively reduces the token budget while preserving answer accuracy. To generate reliable, high-fidelity supervision, we first train a dedicated semantically-preserved compressor on mathematical CoT data with fine-grained annotations. An LLM is then fine-tuned on these compressed pairs via a mixed-ratio supervised fine-tuning (SFT), teaching it to follow a spectrum of compression budgets and providing a stable initialization for reinforcement learning (RL). We further propose Constrained and Hierarchical Ratio Policy Optimization (CHRPO) to explicitly incentivize question-solving ability under lower budgets by a hierarchical reward. Experiments on three mathematical reasoning benchmarks show the superiority of Extra-CoT. For example, on MATH-500 using Qwen3-1.7B, Extra-CoT achieves over 73\% token reduction with an accuracy improvement of 0.6\%, significantly outperforming state-of-the-art (SOTA) methods. Our source codes have been released at https://github.com/Mwie1024/Extra-CoT.
format Preprint
id arxiv_https___arxiv_org_abs_2602_08324
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publishDate 2026
record_format arxiv
spellingShingle Towards Efficient Large Language Reasoning Models via Extreme-Ratio Chain-of-Thought Compression
Tang, Yuntian
Jia, Bohan
Huang, Wenxuan
Zhang, Lianyue
Xie, Jiao
Li, Wenxi
Li, Wei
Hu, Jie
Ji, Xinghao Chen Rongrong
Lin, Shaohui
Machine Learning
Chain-of-Thought (CoT) reasoning successfully enhances the reasoning capabilities of Large Language Models (LLMs), yet it incurs substantial computational overhead for inference. Existing CoT compression methods often suffer from a critical loss of logical fidelity at high compression ratios, resulting in significant performance degradation. To achieve high-fidelity, fast reasoning, we propose a novel EXTreme-RAtio Chain-of-Thought Compression framework, termed Extra-CoT, which aggressively reduces the token budget while preserving answer accuracy. To generate reliable, high-fidelity supervision, we first train a dedicated semantically-preserved compressor on mathematical CoT data with fine-grained annotations. An LLM is then fine-tuned on these compressed pairs via a mixed-ratio supervised fine-tuning (SFT), teaching it to follow a spectrum of compression budgets and providing a stable initialization for reinforcement learning (RL). We further propose Constrained and Hierarchical Ratio Policy Optimization (CHRPO) to explicitly incentivize question-solving ability under lower budgets by a hierarchical reward. Experiments on three mathematical reasoning benchmarks show the superiority of Extra-CoT. For example, on MATH-500 using Qwen3-1.7B, Extra-CoT achieves over 73\% token reduction with an accuracy improvement of 0.6\%, significantly outperforming state-of-the-art (SOTA) methods. Our source codes have been released at https://github.com/Mwie1024/Extra-CoT.
title Towards Efficient Large Language Reasoning Models via Extreme-Ratio Chain-of-Thought Compression
topic Machine Learning
url https://arxiv.org/abs/2602.08324