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

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Main Authors: Arredondo, Felipe de Jesus Felix, Ucan-Puc, Alejandro, Noguez, Carlos Astengo
Format: Preprint
Published: 2026
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author Arredondo, Felipe de Jesus Felix
Ucan-Puc, Alejandro
Noguez, Carlos Astengo
author_facet Arredondo, Felipe de Jesus Felix
Ucan-Puc, Alejandro
Noguez, Carlos Astengo
contents 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.
format Preprint
id arxiv_https___arxiv_org_abs_2603_04625
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle K-Means as a Radial Basis function Network: a Variational and Gradient-based Equivalence
Arredondo, Felipe de Jesus Felix
Ucan-Puc, Alejandro
Noguez, Carlos Astengo
Machine Learning
Statistics Theory
62H30 62H30 62H30 62H30, 62F12, 49J45, 68T05
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.
title K-Means as a Radial Basis function Network: a Variational and Gradient-based Equivalence
topic Machine Learning
Statistics Theory
62H30 62H30 62H30 62H30, 62F12, 49J45, 68T05
url https://arxiv.org/abs/2603.04625