Dynamical Regimes of Discrete Diffusion Models

Fuente: arXiv
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Autori principali: Takahashi, Tomoei, Takahashi, Takashi, Kabashima, Yoshiyuki
Natura: Preprint
Pubblicazione: 2026
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author Takahashi, Tomoei
Takahashi, Takashi
Kabashima, Yoshiyuki
author_facet Takahashi, Tomoei
Takahashi, Takashi
Kabashima, Yoshiyuki
contents Diffusion models generate high-dimensional data such as images by learning a process that gradually removes noise from corrupted data. Recent studies have shown that the backward dynamics of diffusion models exhibit two characteristic transitions: the speciation transition, at which generated samples begin to capture the global structure of the training data, and the collapse transition, at which the generation dynamics starts committing to individual training samples. While these transitions have been theoretically analyzed for continuous data, the same theoretical criteria have not been applied for discrete diffusion models, which are diffusion models for discrete data. In this work, we propose a simple effective model for discrete diffusion models trained on two-class Ising variable data with a general mixture ratio and analyze its backward dynamics using methods from statistical mechanics. We show that, as in the previous study on continuous data, the speciation transition can be determined through a second-order phase transition analysis using high-temperature expansion, while the collapse transition corresponds to a condensation transition described by the Random Energy Model. An analytical expression for the speciation time is obtained, and we show that its scaling becomes consistent with that of the continuous case when the noise increases with time as in practical diffusion models. These theoretical predictions are confirmed by numerical simulations and experiments with trained discrete diffusion models on real datasets. These results suggest that the original theoretical framework for continuous data remain valid for discrete data, and may provide a useful starting point for the statistical-mechanics analysis of discrete generative diffusion in more realistic settings.
format Preprint
id arxiv_https___arxiv_org_abs_2604_10961
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Dynamical Regimes of Discrete Diffusion Models
Takahashi, Tomoei
Takahashi, Takashi
Kabashima, Yoshiyuki
Statistical Mechanics
Diffusion models generate high-dimensional data such as images by learning a process that gradually removes noise from corrupted data. Recent studies have shown that the backward dynamics of diffusion models exhibit two characteristic transitions: the speciation transition, at which generated samples begin to capture the global structure of the training data, and the collapse transition, at which the generation dynamics starts committing to individual training samples. While these transitions have been theoretically analyzed for continuous data, the same theoretical criteria have not been applied for discrete diffusion models, which are diffusion models for discrete data. In this work, we propose a simple effective model for discrete diffusion models trained on two-class Ising variable data with a general mixture ratio and analyze its backward dynamics using methods from statistical mechanics. We show that, as in the previous study on continuous data, the speciation transition can be determined through a second-order phase transition analysis using high-temperature expansion, while the collapse transition corresponds to a condensation transition described by the Random Energy Model. An analytical expression for the speciation time is obtained, and we show that its scaling becomes consistent with that of the continuous case when the noise increases with time as in practical diffusion models. These theoretical predictions are confirmed by numerical simulations and experiments with trained discrete diffusion models on real datasets. These results suggest that the original theoretical framework for continuous data remain valid for discrete data, and may provide a useful starting point for the statistical-mechanics analysis of discrete generative diffusion in more realistic settings.
title Dynamical Regimes of Discrete Diffusion Models
topic Statistical Mechanics
url https://arxiv.org/abs/2604.10961