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Autores principales: Wang, Jialu, Peters, Heinrich, Butt, Asad A., Hashemi, Navid, Hashemi, Alireza, Ghari, Pouya M., Hoover, Joseph, Rae, James, Dehghani, Morteza
Formato: Preprint
Publicado: 2026
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Acceso en línea:https://arxiv.org/abs/2603.10009
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author Wang, Jialu
Peters, Heinrich
Butt, Asad A.
Hashemi, Navid
Hashemi, Alireza
Ghari, Pouya M.
Hoover, Joseph
Rae, James
Dehghani, Morteza
author_facet Wang, Jialu
Peters, Heinrich
Butt, Asad A.
Hashemi, Navid
Hashemi, Alireza
Ghari, Pouya M.
Hoover, Joseph
Rae, James
Dehghani, Morteza
contents Despite their sophisticated general-purpose capabilities, Large Language Models (LLMs) often fail to align with diverse individual preferences because standard post-training methods, like Reinforcement Learning with Human Feedback (RLHF), optimize for a single, global objective. While Group Relative Policy Optimization (GRPO) is a widely adopted on-policy reinforcement learning framework, its group-based normalization implicitly assumes that all samples are exchangeable, inheriting this limitation in personalized settings. This assumption conflates distinct user reward distributions and systematically biases learning toward dominant preferences while suppressing minority signals. To address this, we introduce Personalized GRPO (P-GRPO), a novel alignment framework that decouples advantage estimation from immediate batch statistics. By normalizing advantages against preference-group-specific reward histories rather than the concurrent generation group, P-GRPO preserves the contrastive signal necessary for learning distinct preferences. We evaluate P-GRPO across diverse tasks and find that it consistently achieves faster convergence and higher rewards than standard GRPO, thereby enhancing its ability to recover and align with heterogeneous preference signals. Our results demonstrate that accounting for reward heterogeneity at the optimization level is essential for building models that faithfully align with diverse human preferences without sacrificing general capabilities.
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institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Personalized Group Relative Policy Optimization for Heterogenous Preference Alignment
Wang, Jialu
Peters, Heinrich
Butt, Asad A.
Hashemi, Navid
Hashemi, Alireza
Ghari, Pouya M.
Hoover, Joseph
Rae, James
Dehghani, Morteza
Machine Learning
Artificial Intelligence
Computation and Language
Despite their sophisticated general-purpose capabilities, Large Language Models (LLMs) often fail to align with diverse individual preferences because standard post-training methods, like Reinforcement Learning with Human Feedback (RLHF), optimize for a single, global objective. While Group Relative Policy Optimization (GRPO) is a widely adopted on-policy reinforcement learning framework, its group-based normalization implicitly assumes that all samples are exchangeable, inheriting this limitation in personalized settings. This assumption conflates distinct user reward distributions and systematically biases learning toward dominant preferences while suppressing minority signals. To address this, we introduce Personalized GRPO (P-GRPO), a novel alignment framework that decouples advantage estimation from immediate batch statistics. By normalizing advantages against preference-group-specific reward histories rather than the concurrent generation group, P-GRPO preserves the contrastive signal necessary for learning distinct preferences. We evaluate P-GRPO across diverse tasks and find that it consistently achieves faster convergence and higher rewards than standard GRPO, thereby enhancing its ability to recover and align with heterogeneous preference signals. Our results demonstrate that accounting for reward heterogeneity at the optimization level is essential for building models that faithfully align with diverse human preferences without sacrificing general capabilities.
title Personalized Group Relative Policy Optimization for Heterogenous Preference Alignment
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2603.10009