MaPPO: Maximum a Posteriori Preference Optimization with Prior Knowledge

Fuente: arXiv
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Auteurs principaux: Lan, Guangchen, Zhang, Sipeng, Wang, Tianle, Zhang, Yuwei, Zhang, Daoan, Wei, Xinpeng, Pan, Xiaoman, Zhang, Hongming, Han, Dong-Jun, Brinton, Christopher G.
Format: Preprint
Publié: 2025
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author Lan, Guangchen
Zhang, Sipeng
Wang, Tianle
Zhang, Yuwei
Zhang, Daoan
Wei, Xinpeng
Pan, Xiaoman
Zhang, Hongming
Han, Dong-Jun
Brinton, Christopher G.
author_facet Lan, Guangchen
Zhang, Sipeng
Wang, Tianle
Zhang, Yuwei
Zhang, Daoan
Wei, Xinpeng
Pan, Xiaoman
Zhang, Hongming
Han, Dong-Jun
Brinton, Christopher G.
contents As the era of large language models (LLMs) unfolds, Preference Optimization (PO) methods have become a central approach to aligning LLMs with human preferences and improving performance. We propose Maximum a Posteriori Preference Optimization (MaPPO), a methodology for learning from preferences that explicitly incorporates prior reward knowledge into the optimization objective. Building on the paradigm employed by Direct Preference Optimization (DPO) and its variants of treating preference learning as a Maximum Likelihood Estimation (MLE) problem, MaPPO integrates prior reward estimates into a principled Maximum a Posteriori (MaP) objective. This not only generalizes DPO and its variants, but also enhances alignment by mitigating the oversimplified binary classification of responses. Additionally, MaPPO introduces no additional hyperparameters, and supports preference optimization in both offline and online settings. In addition, MaPPO can be used as a plugin for DPO variants, including widely used SimPO, IPO and CPO, and produce consistent improvements. Extensive empirical evaluations of different model sizes and model series on three standard benchmarks (MT-Bench, AlpacaEval 2.0, and Arena-Hard) demonstrate consistent improvements in alignment performance without sacrificing computational efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2507_21183
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle MaPPO: Maximum a Posteriori Preference Optimization with Prior Knowledge
Lan, Guangchen
Zhang, Sipeng
Wang, Tianle
Zhang, Yuwei
Zhang, Daoan
Wei, Xinpeng
Pan, Xiaoman
Zhang, Hongming
Han, Dong-Jun
Brinton, Christopher G.
Machine Learning
Artificial Intelligence
Computation and Language
I.2.6; I.2.7
As the era of large language models (LLMs) unfolds, Preference Optimization (PO) methods have become a central approach to aligning LLMs with human preferences and improving performance. We propose Maximum a Posteriori Preference Optimization (MaPPO), a methodology for learning from preferences that explicitly incorporates prior reward knowledge into the optimization objective. Building on the paradigm employed by Direct Preference Optimization (DPO) and its variants of treating preference learning as a Maximum Likelihood Estimation (MLE) problem, MaPPO integrates prior reward estimates into a principled Maximum a Posteriori (MaP) objective. This not only generalizes DPO and its variants, but also enhances alignment by mitigating the oversimplified binary classification of responses. Additionally, MaPPO introduces no additional hyperparameters, and supports preference optimization in both offline and online settings. In addition, MaPPO can be used as a plugin for DPO variants, including widely used SimPO, IPO and CPO, and produce consistent improvements. Extensive empirical evaluations of different model sizes and model series on three standard benchmarks (MT-Bench, AlpacaEval 2.0, and Arena-Hard) demonstrate consistent improvements in alignment performance without sacrificing computational efficiency.
title MaPPO: Maximum a Posteriori Preference Optimization with Prior Knowledge
topic Machine Learning
Artificial Intelligence
Computation and Language
I.2.6; I.2.7
url https://arxiv.org/abs/2507.21183