arXiv:2508.10944stat.MLcs.LG2025-08被引 1

提出新型条件扩散模型,实现非渐近收敛分析与理论保证。

Non-asymptotic convergence bound of conditional diffusion models

  • 将预训练模型嵌入扩散框架,精准建模条件分布
  • 在Lipschitz条件下,给出生成分布与真实分布的上界误差
  • 适用于需要理论保障的生成建模场景

基于条件扩散模型的学习与生成已成为近年研究热点。尽管该类模型在加速算法和生成质量方面取得显著进展,但缺乏非渐近性质限制了其理论发展。为此,本文聚焦于分类与回归领域的条件扩散模型(CARD),旨在学习给定输入x(记为Y|X)下的原始分布。创新性地将预训练模型f_ϕ(x)融入原始扩散模型框架,使模型能精确捕捉给定f_ϕ(x)的原始条件分布(即Y|f_ϕ(x))。当f_ϕ(x)表现良好时,Y|f_ϕ(x)可近似于Y|X。理论上,我们推导了CARD的随机微分方程,并基于福克-普兰克方程建立其广义形式,构建了坚实的分析基础。主要在Lipschitz假设下,利用二阶Wasserstein距离,证明了原始分布与生成分布之间的上界误差。此外,在原分布满足轻尾假设的条件下,进一步推导出真实得分函数与网络估计值之间收敛的上界。

原文摘要 · Abstract (English)

Learning and generating various types of data based on conditional diffusion models has been a research hotspot in recent years. Although conditional diffusion models have made considerable progress in improving acceleration algorithms and enhancing generation quality, the lack of non-asymptotic properties has hindered theoretical research. To address this gap, we focus on a conditional diffusion model within the domains of classification and regression (CARD), which aims to learn the original distribution with given input x (denoted as Y|X). It innovatively integrates a pre-trained model f_ϕ(x) into the original diffusion model framework, allowing it to precisely capture the original conditional distribution given f (expressed as Y|f_ϕ(x)). Remarkably, when f_ϕ(x) performs satisfactorily, Y|f_ϕ(x) closely approximates Y|X. Theoretically, we deduce the stochastic differential equations of CARD and establish its generalized form predicated on the Fokker-Planck equation, thereby erecting a firm theoretical foundation for analysis. Mainly under the Lipschitz assumptions, we utilize the second-order Wasserstein distance to demonstrate the upper error bound between the original and the generated conditional distributions. Additionally, by appending assumptions such as light-tailedness to the original distribution, we derive the convergence upper bound between the true value analogous to the score function and the corresponding network-estimated value.

扩散模型条件生成理论分析

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