Simulation-free and finite-time diffusion model

arXiv:2608.03117 · cs.LG · Submitted 2026-08-04 · Read on arXiv

cs.LG

Submitted: 2026-08-04

Updated: 2026-08-31

Code: https://github.com/kentarokaba/sfft-diffusion

License: http://creativecommons.org/licenses/by/4.0/

The gist: The performance of generative diffusion models is determined by the choice of the reference diffusion process connecting the empirical and prior distributions.

Terminology

Abstract

The performance of generative diffusion models is determined by the choice of the reference diffusion process connecting the empirical and prior distributions. Conventional approaches typically trade off simulation-free training against finite-time generation. We propose a framework for designing the reference process that achieves both simultaneously. The key idea is to prescribe tractable time-dependent conditional distributions and then construct the reference process realizing them as its marginals. This framework reveals that score matching is not fundamental to diffusion-model training but instead emerges naturally through reversal of the reference process. We further show that conditional flow matching arises as the small-noise limit of the proposed framework.

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