arXiv:2605.08882cs.LG2026-05

提出离散流匹配的收敛性保证,理论更宽松且依赖更小。

Discrete Flow Matching: Convergence Guarantees Under Minimal Assumptions

  • 基于近似误差假设,不依赖传统得分函数假设。
  • 给出非渐近的KL散度与总变差距离上界。
  • 适用于低维高词表场景,适合关注理论严谨性的研究者。

流匹配是近年来流行的生成模型,用于从源分布 $μ_0$ 模拟目标分布 $μ_1$。该框架依赖于 $μ_0$ 与 $μ_1$ 间的固定耦合,以及确定性或随机桥来定义两者之间的插值过程。通过估计其马尔可夫投影的转移速率或生成器,可近似采样该过程的时间边际分布。该框架已被扩展至离散源与目标分布,称为离散流匹配(DFM)。然而,此类模型的理论保证仍较稀缺。本文研究了在 $\mathbb{Z}_m^d = \{0,\ldots,m-1\}^d$ 上的两种DFM模型,通过时间离散化采样,并推导出两者的非渐近界。与先前工作不同,本文在早期停止条件下建立了目标分布的非渐近KL散度上界,同时给出了相对于真实目标分布的总变差距离显式收敛保证。这些界仅依赖于近似误差假设,放宽了以往工作中的得分函数假设,且对词汇量 $m$ 和维度 $d$ 的依赖更优。

原文摘要 · Abstract (English)

Flow Matching has recently emerged as a popular class of generative models for simulating a target distribution $μ_1$ from samples drawn from a source distribution $μ_0$. This framework relies on a fixed coupling between $μ_0$ and $μ_1$, and on a deterministic or stochastic bridge to define an interpolating process between the two distributions. The time marginals of this process can then be approximately sampled by estimating the transition rates, or more generally the generator, of its Markovian projection. This framework has recently been extended to the case of discrete source and target distributions, under the name Discrete Flow Matching (DFM). However, theoretical guarantees for such models remain scarce. In this paper, we study two DFM models on $\mathbb{Z}_m^d = \{0,\ldots,m-1\}^d$, sampled through time discretization, and derive non-asymptotic associated bounds for both of them. In contrast to previous work, we establish non-asymptotic bounds in Kullback--Leibler divergence for the early-stopped version of the target distribution. We also derive explicit convergence guarantees in total variation distance with respect to the true target distribution. Importantly, these bounds rely only on an approximation error assumption, relaxing standard score assumptions used in earlier works, while also yielding improved dependence on the vocabulary size $m$ and the dimension $d$.

生成模型流匹配理论分析

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