SSPO: Self-traced Step-wise Preference Optimization for Process Supervision and Reasoning Compression

Fuente: arXiv
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Main Authors: Xu, Yuyang, Cheng, Yi, Ying, Haochao, Du, Zhuoyun, Hu, Renjun, Shi, Xing, Lin, Wei, Wu, Jian
Format: Preprint
Published: 2025
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author Xu, Yuyang
Cheng, Yi
Ying, Haochao
Du, Zhuoyun
Hu, Renjun
Shi, Xing
Lin, Wei
Wu, Jian
author_facet Xu, Yuyang
Cheng, Yi
Ying, Haochao
Du, Zhuoyun
Hu, Renjun
Shi, Xing
Lin, Wei
Wu, Jian
contents Test-time scaling has proven effective in further enhancing the performance of pretrained Large Language Models (LLMs). However, mainstream post-training methods (i.e., reinforcement learning (RL) with chain-of-thought (CoT) reasoning) often incur substantial computational overhead due to auxiliary models and overthinking. In this paper, we empirically reveal that the incorrect answers partially stem from verbose reasoning processes lacking correct self-fix, where errors accumulate across multiple reasoning steps. To this end, we propose Self-traced Step-wise Preference Optimization (SSPO), a pluggable RL process supervision framework that enables fine-grained optimization of each reasoning step. Specifically, SSPO requires neither auxiliary models nor stepwise manual annotations. Instead, it leverages step-wise preference signals generated by the model itself to guide the optimization process for reasoning compression. Experiments demonstrate that the generated reasoning sequences from SSPO are both accurate and succinct, effectively mitigating overthinking behaviors without compromising model performance across diverse domains and languages.
format Preprint
id arxiv_https___arxiv_org_abs_2508_12604
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SSPO: Self-traced Step-wise Preference Optimization for Process Supervision and Reasoning Compression
Xu, Yuyang
Cheng, Yi
Ying, Haochao
Du, Zhuoyun
Hu, Renjun
Shi, Xing
Lin, Wei
Wu, Jian
Machine Learning
Artificial Intelligence
Test-time scaling has proven effective in further enhancing the performance of pretrained Large Language Models (LLMs). However, mainstream post-training methods (i.e., reinforcement learning (RL) with chain-of-thought (CoT) reasoning) often incur substantial computational overhead due to auxiliary models and overthinking. In this paper, we empirically reveal that the incorrect answers partially stem from verbose reasoning processes lacking correct self-fix, where errors accumulate across multiple reasoning steps. To this end, we propose Self-traced Step-wise Preference Optimization (SSPO), a pluggable RL process supervision framework that enables fine-grained optimization of each reasoning step. Specifically, SSPO requires neither auxiliary models nor stepwise manual annotations. Instead, it leverages step-wise preference signals generated by the model itself to guide the optimization process for reasoning compression. Experiments demonstrate that the generated reasoning sequences from SSPO are both accurate and succinct, effectively mitigating overthinking behaviors without compromising model performance across diverse domains and languages.
title SSPO: Self-traced Step-wise Preference Optimization for Process Supervision and Reasoning Compression
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2508.12604