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arXiv 2405.15643stat.MLcs.LGcs.NAmath.APmath.NAmath.PR
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条件分数的无条件表示在无限维线性逆问题中

An Unconditional Representation of the Conditional Score in Infinite-Dimensional Linear Inverse Problems

School of Engineering Science(工程科学学院);Lappeenranta-Lahti University of Technology(拉普兰塔-拉赫蒂技术大学);Vienna University of Technology (TU Wien)(维也纳技术大学);Department of Mathematics and Statistics(数学与统计学系);University of Helsinki(赫尔辛基大学);Department of Computational and Applied Mathematics(计算与应用数学系);Rice University(里士满大学)

Fabian Schneider, Duc-Lam Duong, Matti Lassas, Maarten V. de Hoop, Tapio Helin

AI总结:

本文提出了一种针对线性逆问题的无条件条件分数表示方法,通过离线训练避免正向模型评估,实现高效且精确的采样。

摘要:

基于分数的扩散模型(SDMs)已发展为一种强大的工具,用于在贝叶斯逆问题中从后验分布进行采样。然而,现有方法往往需要多次评估正向映射来生成一个样本,这导致在大规模逆问题中产生显著的计算成本。为了解决这个问题,我们提出了一种针对线性逆问题的条件分数函数的无条件表示(UCoS),该方法在采样过程中避免了正向模型的评估,而是将计算努力转移到离线训练阶段。在此阶段,基于线性正向算子学习了一个任务相关的分数函数。关键的是,我们证明了可以通过训练(无条件)分数的仿射变换来精确推导条件分数,从而消除了对条件分数近似的需求。我们的方法是在无限维函数空间中建立的,使其本质上与离散化无关。我们通过严谨的收敛分析来支持这种公式化,证明了UCoS超越了任何特定的离散化。最后,我们通过高维计算断层摄影(CT)和图像去模糊实验验证了UCoS,展示了其可扩展性和准确性。

英文摘要:

Score-based diffusion models (SDMs) have emerged as a powerful tool for sampling from the posterior distribution in Bayesian inverse problems. However, existing methods often require multiple evaluations of the forward mapping to generate a single sample, resulting in significant computational costs for large-scale inverse problems. To address this, we propose an unconditional representation of the conditional score function (UCoS) tailored to linear inverse problems, which avoids forward model evaluations during sampling by shifting computational effort to an offline training phase. In this phase, a \emph{task-dependent} score function is learned based on the linear forward operator. Crucially, we show that the conditional score can be derived \emph{exactly} from a trained (unconditional) score using affine transformations, eliminating the need for conditional score approximations. Our approach is formulated in infinite-dimensional function spaces, making it inherently discretization-invariant. We support this formulation with a rigorous convergence analysis that justifies UCoS beyond any specific discretization. Finally we validate UCoS through high-dimensional computed tomography (CT) and image deblurring experiments, demonstrating both scalability and accuracy.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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