arXiv:2603.04625cs.LGmath.ST2026-03

K-Means与RBF网络等价,可直接嵌入深度学习联合优化聚类与表示。

K-Means as a Radial Basis function Network: a Variational and Gradient-based Equivalence

  • 将K-Means重参数化为平滑加权损失,实现与RBF网络的变分等价
  • 在温度σ趋近0时,RBF梯度更新精确复现K-Means中心更新规则
  • 引入Entmax-1.5稳定低温度下的数值计算,保持Voronoi划分结构

本文建立了经典K-Means算法与可微分径向基函数(RBF)神经网络之间的严格变分与梯度等价关系。通过重参数化K-Means目标函数,并将其扭曲泛函嵌入平滑加权损失,证明当温度参数σ趋于零时,RBF目标Γ-收敛至K-Means解。进一步表明,RBF中心的梯度更新规则与K-Means中心更新完全一致,极限下诱导相同的训练轨迹。为解决低温度下Softmax变换的数值不稳定性,提出集成Entmax-1.5,确保多项式收敛的同时保留底层Voronoi划分结构。该成果弥合了离散划分与连续优化间的概念鸿沟,使K-Means可直接嵌入深度学习架构中,实现表示与聚类的端到端联合优化。在多种合成几何数据上的实证验证表明,软RBF中心单调收敛至K-Means不动点,构建了一个统一的可微聚类框架。

原文摘要 · Abstract (English)

This work establishes a rigorous variational and gradient-based equivalence between the classical K-Means algorithm and differentiable Radial Basis Function (RBF) neural networks with smooth responsibilities. By reparameterizing the K-Means objective and embedding its distortion functional into a smooth weighted loss, we prove that the RBF objective $Γ$-converges to the K-Means solution as the temperature parameter $σ$ vanishes. We further demonstrate that the gradient-based updates of the RBF centers recover the exact K-Means centroid update rule and induce identical training trajectories in the limit. To address the numerical instability of the Softmax transformation in the low-temperature regime, we propose the integration of Entmax-1.5, which ensures stable polynomial convergence while preserving the underlying Voronoi partition structure. These results bridge the conceptual gap between discrete partitioning and continuous optimization, enabling K-Means to be embedded directly into deep learning architectures for the joint optimization of representations and clusters. Empirical validation across diverse synthetic geometries confirms a monotone collapse of soft RBF centroids toward K-Means fixed points, providing a unified framework for end-to-end differentiable clustering.

聚类RBF网络可微分优化

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