arXiv:2608.02799stat.MLcs.AI2026-08

用非标准分析构建扩散生成模型的统一框架,连接离散与连续过程。

A Hyperfinite Framework for Score-Based Generative Modeling

  • 基于超有限网格构造内部扩散过程,推导出反向时间漂移项。
  • 证明最小化内部得分匹配目标可恢复反向动态所需得分函数。
  • 揭示高阶一致性与增量分布四阶矩的关系,高斯情形消去主导发散项。

得分驱动的扩散模型通常基于连续时间随机微分方程和测度论随机分析。本文在非标准分析框架下,提出一种超有限形式的得分生成建模方法。从超有限网格上的内部扩散过程出发,推导其对应的无穷小生成算子,并建立与经典福克-普朗克方程的对应关系。进一步获得一个超有限反向均值恒等式,导出反向时间漂移项,实现反向SDE的构造性推导。基于此,我们证明最小化内部得分匹配目标可恢复反向动力学所需的得分函数,直接在超有限层面建立得分估计与生成采样之间的联系。在合理假设下,还推导出超有限吉尔萨诺夫公式,建立似然优化与费雪散度目标之间的关系。最后,分析超有限动态的二阶一致性,表明主导修正项显式依赖于增量分布的四阶矩,当高斯情形κ=3时,消除主导色散贡献。这些结果共同构成一个统一的超有限框架,连接离散网格动态、反向扩散、得分匹配与基于似然的表述,为后续拓展奠定基础。

原文摘要 · Abstract (English)

Score-based diffusion models are typically formulated using continuous-time stochastic differential equations and measure-theoretic stochastic calculus. In this paper, we develop a hyperfinite formulation of score-based generative modeling within the framework of Nonstandard Analysis. Starting from an internal diffusion process on a hyperfinite grid, we derive the associated infinitesimal generator and establish its correspondence with the classical Fokker--Planck equation. We then obtain a hyperfinite backward-mean identity that yields the reverse-time drift and provides a constructive derivation of the reverse-time SDE. Building on these results, we show that minimization of an internal score-matching objective recovers the score function required by the reverse-time dynamics, thereby connecting score estimation with generative sampling directly at the hyperfinite level. Under suitable assumptions, we further derive a hyperfinite Girsanov formula and establish a relationship between likelihood optimization and Fisher-divergence objectives. Finally, we analyze the second-order consistency of the hyperfinite dynamics and show that the leading correction term depends explicitly on the fourth moment of the increment distribution, with the Gaussian value $κ=3$ eliminating the leading dispersion contribution. Taken together, these results provide a unified hyperfinite framework for diffusion-based generative modeling--while laying foundations for further extensions--that links discrete grid dynamics, reverse-time diffusion, score matching, and likelihood-based formulations within a common nonstandard setting.

扩散模型非标准分析得分匹配生成模型

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