Direct Density Ratio Optimization: A Statistically Consistent Approach to Aligning Large Language Models

Fuente: arXiv
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Auteurs principaux: Higuchi, Rei, Suzuki, Taiji
Format: Preprint
Publié: 2025
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author Higuchi, Rei
Suzuki, Taiji
author_facet Higuchi, Rei
Suzuki, Taiji
contents Aligning large language models (LLMs) with human preferences is crucial for safe deployment, yet existing methods assume specific preference models like Bradley-Terry model. This assumption leads to statistical inconsistency, where more data doesn't guarantee convergence to true human preferences. To address this critical gap, we introduce a novel alignment method Direct Density Ratio Optimization (DDRO). DDRO directly estimates the density ratio between preferred and unpreferred output distributions, circumventing the need for explicit human preference modeling. We theoretically prove that DDRO is statistically consistent, ensuring convergence to the true preferred distribution as the data size grows, regardless of the underlying preference structure. Experiments demonstrate that DDRO achieves superior performance compared to existing methods on many major benchmarks. DDRO unlocks the potential for truly data-driven alignment, paving the way for more reliable and human-aligned LLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2505_07558
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Direct Density Ratio Optimization: A Statistically Consistent Approach to Aligning Large Language Models
Higuchi, Rei
Suzuki, Taiji
Machine Learning
Computation and Language
Aligning large language models (LLMs) with human preferences is crucial for safe deployment, yet existing methods assume specific preference models like Bradley-Terry model. This assumption leads to statistical inconsistency, where more data doesn't guarantee convergence to true human preferences. To address this critical gap, we introduce a novel alignment method Direct Density Ratio Optimization (DDRO). DDRO directly estimates the density ratio between preferred and unpreferred output distributions, circumventing the need for explicit human preference modeling. We theoretically prove that DDRO is statistically consistent, ensuring convergence to the true preferred distribution as the data size grows, regardless of the underlying preference structure. Experiments demonstrate that DDRO achieves superior performance compared to existing methods on many major benchmarks. DDRO unlocks the potential for truly data-driven alignment, paving the way for more reliable and human-aligned LLMs.
title Direct Density Ratio Optimization: A Statistically Consistent Approach to Aligning Large Language Models
topic Machine Learning
Computation and Language
url https://arxiv.org/abs/2505.07558