Non-asymptotic error bounds for probability flow ODEs under weak log-concavity

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Main Authors: Kremling, Gitte, Iafrate, Francesco, Taheri, Mahsa, Lederer, Johannes
Format: Preprint
Published: 2025
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author Kremling, Gitte
Iafrate, Francesco
Taheri, Mahsa
Lederer, Johannes
author_facet Kremling, Gitte
Iafrate, Francesco
Taheri, Mahsa
Lederer, Johannes
contents Score-based generative modeling, implemented through probability flow ODEs, has shown impressive results in numerous practical settings. However, most convergence guarantees rely on restrictive regularity assumptions on the target distribution -- such as strong log-concavity or bounded support. This work establishes non-asymptotic convergence bounds in the 2-Wasserstein distance for a general class of probability flow ODEs under considerably weaker assumptions: weak log-concavity and Lipschitz continuity of the score function. Our framework accommodates non-log-concave distributions, such as Gaussian mixtures, and explicitly accounts for initialization errors, score approximation errors, and effects of discretization via an exponential integrator scheme. Bridging a key theoretical challenge in diffusion-based generative modeling, our results extend convergence theory to more realistic data distributions and practical ODE solvers. We provide concrete guarantees for the efficiency and correctness of the sampling algorithm, complementing the empirical success of diffusion models with rigorous theory. Moreover, from a practical perspective, our explicit rates might be helpful in choosing hyperparameters, such as the step size in the discretization.
format Preprint
id arxiv_https___arxiv_org_abs_2510_17608
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Non-asymptotic error bounds for probability flow ODEs under weak log-concavity
Kremling, Gitte
Iafrate, Francesco
Taheri, Mahsa
Lederer, Johannes
Machine Learning
Statistics Theory
Score-based generative modeling, implemented through probability flow ODEs, has shown impressive results in numerous practical settings. However, most convergence guarantees rely on restrictive regularity assumptions on the target distribution -- such as strong log-concavity or bounded support. This work establishes non-asymptotic convergence bounds in the 2-Wasserstein distance for a general class of probability flow ODEs under considerably weaker assumptions: weak log-concavity and Lipschitz continuity of the score function. Our framework accommodates non-log-concave distributions, such as Gaussian mixtures, and explicitly accounts for initialization errors, score approximation errors, and effects of discretization via an exponential integrator scheme. Bridging a key theoretical challenge in diffusion-based generative modeling, our results extend convergence theory to more realistic data distributions and practical ODE solvers. We provide concrete guarantees for the efficiency and correctness of the sampling algorithm, complementing the empirical success of diffusion models with rigorous theory. Moreover, from a practical perspective, our explicit rates might be helpful in choosing hyperparameters, such as the step size in the discretization.
title Non-asymptotic error bounds for probability flow ODEs under weak log-concavity
topic Machine Learning
Statistics Theory
url https://arxiv.org/abs/2510.17608