arXiv:2505.10466stat.MLcs.LG2025-05被引 1

FlowVAT让变分推断自动找多模态后验,无需调温度参数。

FlowVAT: Normalizing Flow Variational Inference with Affine-Invariant Tempering

  • 用条件流模型同时调节基分布和目标分布温度
  • 在2~20维多模态分布上找到更多模式,ELBO更优
  • 免调参、无退火调度,适合复杂后验的全自动推断

多模态高维后验分布给变分推断带来挑战,导致模式聚焦与崩溃问题,尽管归一化流理论上表达力强。传统退火方法需温度调度和超参数调优,难以实现真正黑盒推断。我们提出FlowVAT,一种基于仿射不变退火的归一化流变分推断方法。该方法同时对基分布和目标分布进行退火,并保持退火下的仿射不变性。通过将归一化流条件于温度,利用过参数神经网络的泛化能力,仅用一个流即可表示一系列温度下的后验分布。这使得在T=1时采样能保留高温下识别出的模式,缓解标准变分方法的模式聚焦行为。在2、10、20维多模态分布上的实验表明,FlowVAT优于传统及自适应退火方法,能发现更多模式并获得更高ELBO值,尤其在高维场景中表现突出。本方法几乎无需超参数调优,也无需退火调度,推动了复杂后验的全自动黑盒变分推断进展。

原文摘要 · Abstract (English)

Multi-modal and high-dimensional posteriors present significant challenges for variational inference, causing mode-seeking behavior and collapse despite the theoretical expressiveness of normalizing flows. Traditional annealing methods require temperature schedules and hyperparameter tuning, falling short of the goal of truly black-box variational inference. We introduce FlowVAT, a conditional tempering approach for normalizing flow variational inference that addresses these limitations. Our method tempers both the base and target distributions simultaneously, maintaining affine-invariance under tempering. By conditioning the normalizing flow on temperature, we leverage overparameterized neural networks' generalization capabilities to train a single flow representing the posterior across a range of temperatures. This preserves modes identified at higher temperatures when sampling from the variational posterior at $T = 1$, mitigating standard variational methods' mode-seeking behavior. In experiments with 2, 10, and 20 dimensional multi-modal distributions, FlowVAT outperforms traditional and adaptive annealing methods, finding more modes and achieving better ELBO values, particularly in higher dimensions where existing approaches fail. Our method requires minimal hyperparameter tuning and does not require an annealing schedule, advancing toward fully-automatic black-box variational inference for complicated posteriors.

变分推断归一化流多模态自动化

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