While score-based generative models (SGMs) have achieved remarkable success in enormous image generation tasks, their mathematical foundations are still limited. In this paper, we analyze the approximation and generalization of SGMs in learning a family of sub-Gaussian probability distributions. We introduce a notion of complexity for probability distributions in terms of their relative density with respect to the standard Gaussian measure. We prove that if the log-relative density can be locally approximated by a neural network whose parameters can be suitably bounded, then the distribution generated by empirical score matching approximates the target distribution in total variation with a dimension-independent rate. We illustrate our theory through examples, which include certain mixtures of Gaussians. An essential ingredient of our proof is to derive a dimension-free deep neural network approximation rate for the true score function associated with the forward process, which is interesting in its own right.

分析使用得分为基础的生成模型在学习一类亚高斯概率分布时的近似和概括性，介绍了相对于标准高斯测度的概率分布的复杂性概念，证明了通过经验得分匹配生成的分布以维度无关的速率近似目标分布。通过包括某些高斯混合的示例说明了理论，证明中的一个基本要素是导出与正向过程相关的真实得分函数的无维度深度神经网络逼近速率，独立成趣。

基于成绩的生成模型在学习亚高斯概率分布族中克服了维度诅咒