Magnetic Preference Optimization: Achieving Last-iterate Convergence for Language Model Alignment

Fuente: arXiv
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Autores principales: Wang, Mingzhi, Ma, Chengdong, Chen, Qizhi, Meng, Linjian, Han, Yang, Xiao, Jiancong, Zhang, Zhaowei, Huo, Jing, Su, Weijie J., Yang, Yaodong
Formato: Preprint
Publicado: 2024
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author Wang, Mingzhi
Ma, Chengdong
Chen, Qizhi
Meng, Linjian
Han, Yang
Xiao, Jiancong
Zhang, Zhaowei
Huo, Jing
Su, Weijie J.
Yang, Yaodong
author_facet Wang, Mingzhi
Ma, Chengdong
Chen, Qizhi
Meng, Linjian
Han, Yang
Xiao, Jiancong
Zhang, Zhaowei
Huo, Jing
Su, Weijie J.
Yang, Yaodong
contents Self-play methods have demonstrated remarkable success in enhancing model capabilities across various domains. In the context of Reinforcement Learning from Human Feedback (RLHF), self-play not only boosts Large Language Model (LLM) performance but also overcomes the limitations of traditional Bradley-Terry (BT) model assumptions by finding the Nash equilibrium (NE) of a preference-based, two-player constant-sum game. However, existing methods either guarantee only average-iterate convergence, incurring high storage and inference costs, or converge to the NE of a regularized game, failing to accurately reflect true human preferences. In this paper, we introduce Magnetic Preference Optimization (MPO), a novel approach capable of achieving last-iterate convergence to the NE of the original game, effectively overcoming the limitations of existing methods. Building upon Magnetic Mirror Descent (MMD), MPO attains a linear convergence rate, making it particularly suitable for fine-tuning LLMs. To ensure our algorithm is both theoretically sound and practically viable, we present a simple yet effective implementation that adapts the theoretical insights to the RLHF setting. Empirical results demonstrate that MPO can significantly enhance the performance of LLMs, highlighting the potential of self-play methods in alignment.
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id arxiv_https___arxiv_org_abs_2410_16714
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Magnetic Preference Optimization: Achieving Last-iterate Convergence for Language Model Alignment
Wang, Mingzhi
Ma, Chengdong
Chen, Qizhi
Meng, Linjian
Han, Yang
Xiao, Jiancong
Zhang, Zhaowei
Huo, Jing
Su, Weijie J.
Yang, Yaodong
Computation and Language
Self-play methods have demonstrated remarkable success in enhancing model capabilities across various domains. In the context of Reinforcement Learning from Human Feedback (RLHF), self-play not only boosts Large Language Model (LLM) performance but also overcomes the limitations of traditional Bradley-Terry (BT) model assumptions by finding the Nash equilibrium (NE) of a preference-based, two-player constant-sum game. However, existing methods either guarantee only average-iterate convergence, incurring high storage and inference costs, or converge to the NE of a regularized game, failing to accurately reflect true human preferences. In this paper, we introduce Magnetic Preference Optimization (MPO), a novel approach capable of achieving last-iterate convergence to the NE of the original game, effectively overcoming the limitations of existing methods. Building upon Magnetic Mirror Descent (MMD), MPO attains a linear convergence rate, making it particularly suitable for fine-tuning LLMs. To ensure our algorithm is both theoretically sound and practically viable, we present a simple yet effective implementation that adapts the theoretical insights to the RLHF setting. Empirical results demonstrate that MPO can significantly enhance the performance of LLMs, highlighting the potential of self-play methods in alignment.
title Magnetic Preference Optimization: Achieving Last-iterate Convergence for Language Model Alignment
topic Computation and Language
url https://arxiv.org/abs/2410.16714