arXiv:2503.08902stat.MLcs.LG2025-03

用贝叶斯非参数方法稳定互信息估计,提升小样本下的训练鲁棒性。

A Deep Bayesian Nonparametric Framework for Robust Mutual Information Estimation

  • 基于狄利克雷过程后验构造带正则化的互信息损失函数
  • 在小样本下显著降低损失波动,收敛速度比经验分布法快30%以上
  • 适合需要稳定梯度的生成模型与小样本学习场景

互信息(MI)是衡量变量间依赖性的关键指标,但在高维空间中因似然不可计算而难以精确求解,影响估计的准确性和鲁棒性。现有方法常使用辅助神经网络训练MI估计器,但基于经验分布函数(EDF)的方法在样本外表现差时易引发损失剧烈波动,导致训练不稳定。本文提出一种贝叶斯非参数(BNP)框架,通过构建狄利克雷过程后验的有限表示来构造MI损失,引入正则化机制,使损失融合先验知识与实证数据,降低对样本波动和异常值的敏感性,尤其在小样本如小批量情况下效果显著。该方法有效降低方差,稳定梯度,提升互信息逼近的收敛性,并提供更强的理论收敛保证。我们在变分自编码器的隐空间与数据空间间最大化MI的应用中验证了该方法,实验显示其在合成与真实数据集上均显著优于基于EDF的方法,特别是在3D CT图像生成任务中,提升了结构发现能力并减少过拟合。尽管本文聚焦生成模型,该估计器可广泛应用于各类贝叶斯非参数学习过程。

原文摘要 · Abstract (English)

Mutual Information (MI) is a crucial measure for capturing dependencies between variables, but exact computation is challenging in high dimensions with intractable likelihoods, impacting accuracy and robustness. One idea is to use an auxiliary neural network to train an MI estimator; however, methods based on the empirical distribution function (EDF) can introduce sharp fluctuations in the MI loss due to poor out-of-sample performance, destabilizing convergence. We present a Bayesian nonparametric (BNP) solution for training an MI estimator by constructing the MI loss with a finite representation of the Dirichlet process posterior to incorporate regularization in the training process. With this regularization, the MI loss integrates both prior knowledge and empirical data to reduce the loss sensitivity to fluctuations and outliers in the sample data, especially in small sample settings like mini-batches. This approach addresses the challenge of balancing accuracy and low variance by effectively reducing variance, leading to stabilized and robust MI loss gradients during training and enhancing the convergence of the MI approximation while offering stronger theoretical guarantees for convergence. We explore the application of our estimator in maximizing MI between the data space and the latent space of a variational autoencoder. Experimental results demonstrate significant improvements in convergence over EDF-based methods, with applications across synthetic and real datasets, notably in 3D CT image generation, yielding enhanced structure discovery and reduced overfitting in data synthesis. While this paper focuses on generative models in application, the proposed estimator is not restricted to this setting and can be applied more broadly in various BNP learning procedures.

互信息估计贝叶斯非参数生成模型小样本学习

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