Self-Rewarding PPO: Aligning Large Language Models with Demonstrations Only

Fuente: arXiv
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Main Authors: Zhang, Qingru, Qiu, Liang, Hong, Ilgee, Xu, Zhenghao, Liu, Tianyi, Li, Shiyang, Zhang, Rongzhi, Li, Zheng, Li, Lihong, Yin, Bing, Zhang, Chao, Chen, Jianshu, Jiang, Haoming, Zhao, Tuo
Format: Preprint
Published: 2025
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author Zhang, Qingru
Qiu, Liang
Hong, Ilgee
Xu, Zhenghao
Liu, Tianyi
Li, Shiyang
Zhang, Rongzhi
Li, Zheng
Li, Lihong
Yin, Bing
Zhang, Chao
Chen, Jianshu
Jiang, Haoming
Zhao, Tuo
author_facet Zhang, Qingru
Qiu, Liang
Hong, Ilgee
Xu, Zhenghao
Liu, Tianyi
Li, Shiyang
Zhang, Rongzhi
Li, Zheng
Li, Lihong
Yin, Bing
Zhang, Chao
Chen, Jianshu
Jiang, Haoming
Zhao, Tuo
contents Supervised fine-tuning (SFT) has emerged as a crucial method for aligning large language models (LLMs) with human-annotated demonstrations. However, SFT, being an off-policy approach similar to behavior cloning, often struggles with overfitting and poor out-of-domain generalization, especially in limited-data scenarios. To address these limitations, we propose Self-Rewarding PPO, a novel fine-tuning method that leverages on-policy techniques to enhance generalization performance. Our approach combines the strengths of SFT and proximal policy optimization (PPO) to achieve more effective alignment from demonstration data. At its core is a reward function designed as the log policy ratio between the SFT model and the pretrained base model. This function serves as an implicit reward signal, using the pretrained policy as a baseline and the SFT policy as a target. By doing so, it enables on-policy fine-tuning without relying on human preference annotations. The integration of this self-rewarding mechanism with PPO addresses key limitations of SFT, improving generalization, data efficiency, and robustness. Our empirical evaluation across a range of natural language processing tasks demonstrates that Self-Rewarding PPO consistently outperforms traditional SFT methods. The results highlight the effectiveness of our approach in aligning LLMs using demonstration data, particularly in scenarios where high-quality annotated data is scarce.
format Preprint
id arxiv_https___arxiv_org_abs_2510_21090
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Self-Rewarding PPO: Aligning Large Language Models with Demonstrations Only
Zhang, Qingru
Qiu, Liang
Hong, Ilgee
Xu, Zhenghao
Liu, Tianyi
Li, Shiyang
Zhang, Rongzhi
Li, Zheng
Li, Lihong
Yin, Bing
Zhang, Chao
Chen, Jianshu
Jiang, Haoming
Zhao, Tuo
Computation and Language
Artificial Intelligence
Machine Learning
Supervised fine-tuning (SFT) has emerged as a crucial method for aligning large language models (LLMs) with human-annotated demonstrations. However, SFT, being an off-policy approach similar to behavior cloning, often struggles with overfitting and poor out-of-domain generalization, especially in limited-data scenarios. To address these limitations, we propose Self-Rewarding PPO, a novel fine-tuning method that leverages on-policy techniques to enhance generalization performance. Our approach combines the strengths of SFT and proximal policy optimization (PPO) to achieve more effective alignment from demonstration data. At its core is a reward function designed as the log policy ratio between the SFT model and the pretrained base model. This function serves as an implicit reward signal, using the pretrained policy as a baseline and the SFT policy as a target. By doing so, it enables on-policy fine-tuning without relying on human preference annotations. The integration of this self-rewarding mechanism with PPO addresses key limitations of SFT, improving generalization, data efficiency, and robustness. Our empirical evaluation across a range of natural language processing tasks demonstrates that Self-Rewarding PPO consistently outperforms traditional SFT methods. The results highlight the effectiveness of our approach in aligning LLMs using demonstration data, particularly in scenarios where high-quality annotated data is scarce.
title Self-Rewarding PPO: Aligning Large Language Models with Demonstrations Only
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2510.21090