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Bibliographic Details
Main Authors: Rochman-Sharabi, Omer, Louppe, Gilles
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2601.21033
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author Rochman-Sharabi, Omer
Louppe, Gilles
author_facet Rochman-Sharabi, Omer
Louppe, Gilles
contents Diffusion models cannot enforce hard constraints, yet applications in the physical sciences demand exact satisfaction of conservation laws, boundary conditions, and observational consistency. In this work, we identify a corrector kernel whose unique stationary distribution is the constrained marginal at each noise level, and approximate it by iteratively projecting through the denoiser and renoising via the forward kernel. The resulting Predict-Project-Renoise (PPR) algorithm enables sampling from pretrained diffusion models under hard constraints. Its three components are each necessary: projecting through the denoiser keeps samples close to the data manifold, while renoising and iterating drive samples toward the constrained marginal. On 2D distributions, the Kuramoto-Sivashinsky equation, and global weather forecasting with a $10^8$-dimensional atmospheric model, PPR simultaneously achieves low constraint violations and high distributional fidelity, a combination that existing methods fail to deliver.
format Preprint
id arxiv_https___arxiv_org_abs_2601_21033
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Predict-Project-Renoise: Sampling Diffusion Models under Hard Constraints
Rochman-Sharabi, Omer
Louppe, Gilles
Machine Learning
Diffusion models cannot enforce hard constraints, yet applications in the physical sciences demand exact satisfaction of conservation laws, boundary conditions, and observational consistency. In this work, we identify a corrector kernel whose unique stationary distribution is the constrained marginal at each noise level, and approximate it by iteratively projecting through the denoiser and renoising via the forward kernel. The resulting Predict-Project-Renoise (PPR) algorithm enables sampling from pretrained diffusion models under hard constraints. Its three components are each necessary: projecting through the denoiser keeps samples close to the data manifold, while renoising and iterating drive samples toward the constrained marginal. On 2D distributions, the Kuramoto-Sivashinsky equation, and global weather forecasting with a $10^8$-dimensional atmospheric model, PPR simultaneously achieves low constraint violations and high distributional fidelity, a combination that existing methods fail to deliver.
title Predict-Project-Renoise: Sampling Diffusion Models under Hard Constraints
topic Machine Learning
url https://arxiv.org/abs/2601.21033