arXiv:2606.24140cs.LG2026-06

提出新采样器,在少计算量下提升离散流匹配生成质量。

A Time-Reparameterized Cumulative Intensity Extrapolation Sampler for Discrete Flow Matching

论文配图:A Time-Reparameterized Cumulative Intensity Extrapolation Sampler for Discrete Flow Matching
图 1 · 摘自论文原文
  • 重参数化时间网格,缓解末期采样僵硬问题。
  • 利用历史输出改进累积强度逼近,精度更高。
  • 每步仅需一次函数计算,适合资源受限场景。

离散流匹配(DFM)通过连续时间马尔可夫链为离散状态空间的生成建模提供了理论框架。实践中,采样常采用τ-跳变等离散化方法,但受限于函数评估次数(NFE)时的高效采样方法仍研究不足。为此,本文提出时间重参数化累积强度外推采样器(TR-CIE),旨在有限NFE下提升采样质量。TR-CIE包含两部分:一是基于噪声调度的时间重参数化,将时间网格按调度缩放,吸收依赖调度的增长项,缓解终期僵硬;二是引入累积强度外推更新规则,复用上一步缓存模型输出作为历史项,提升非均匀时间网格上逐步累积强度的近似精度。我们提供局部近似误差界与收敛性分析。该采样器每步仅需一次NFE,不增加额外模型评估。在合成任务、文本生成和文本到图像基准上的实验表明,该方法在有限NFE下显著提升采样质量。

原文摘要 · Abstract (English)

Discrete flow matching (DFM) provides a principled framework for generative modeling on discrete state spaces via continuous-time Markov chain dynamics. In practice, sampling for DFM commonly employs discretizations such as $τ$-leaping, yet efficient sampling methods under a limited number of function evaluations (NFE) remain less studied. To address this gap, we propose the Time-Reparameterized Cumulative Intensity Extrapolation (TR-CIE) sampler, which aims to improve sampling quality when function evaluations are restricted. TR-CIE consists of two components. First, a schedule-based time reparameterization rescales the time grid according to the noise schedule. Under standard factorized DFM rate parameterizations, this transformation of variables absorbs the schedule-dependent growth term and mitigates stiffness near the terminal sampling stage. Second, we introduce a cumulative-intensity extrapolation updating rule. By reusing cached model outputs from the previous step as a history term, this improves the approximation of stepwise cumulative intensities on the resulting non-uniform time grid. We provide a theoretical analysis that bounds the local approximation error of cumulative intensities and establishes convergence results. The resulting sampler requires one NFE per step and introduces no additional model evaluations compared to the standard $τ$-leaping sampler. Extensive experiments on synthetic tasks, text generation, and text-to-image benchmarks demonstrate that our method improves sampling quality under limited NFE.

生成模型离散流匹配采样优化

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