Multi-Community Spectral Clustering for Geometric Graphs

Fuente: arXiv
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Main Authors: Allem, Luiz Emilio, Avrachenkov, Konstantin, Hoppen, Carlos, Manjunath, Hariprasad, Sibemberg, Lucas Siviero
Format: Preprint
Published: 2025
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author Allem, Luiz Emilio
Avrachenkov, Konstantin
Hoppen, Carlos
Manjunath, Hariprasad
Sibemberg, Lucas Siviero
author_facet Allem, Luiz Emilio
Avrachenkov, Konstantin
Hoppen, Carlos
Manjunath, Hariprasad
Sibemberg, Lucas Siviero
contents In this paper, we consider the soft geometric block model (SGBM) with a fixed number $k \geq 2$ of homogeneous communities in the dense regime, and we introduce a spectral clustering algorithm for community recovery on graphs generated by this model. Given such a graph, the algorithm produces an embedding into $\mathbb{R}^{k-1}$ using the eigenvectors associated with the $k-1$ eigenvalues of the adjacency matrix of the graph that are closest to a value determined by the parameters of the model. It then applies $k$-means clustering to the embedding. We prove weak consistency and show that a simple local refinement step ensures strong consistency. A key ingredient is an application of a non-standard version of Davis-Kahan theorem to control eigenspace perturbations when eigenvalues are not simple. We also analyze the limiting spectrum of the adjacency matrix, using a combination of combinatorial and matrix techniques.
format Preprint
id arxiv_https___arxiv_org_abs_2508_00893
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Multi-Community Spectral Clustering for Geometric Graphs
Allem, Luiz Emilio
Avrachenkov, Konstantin
Hoppen, Carlos
Manjunath, Hariprasad
Sibemberg, Lucas Siviero
Social and Information Networks
Machine Learning
Probability
Spectral Theory
In this paper, we consider the soft geometric block model (SGBM) with a fixed number $k \geq 2$ of homogeneous communities in the dense regime, and we introduce a spectral clustering algorithm for community recovery on graphs generated by this model. Given such a graph, the algorithm produces an embedding into $\mathbb{R}^{k-1}$ using the eigenvectors associated with the $k-1$ eigenvalues of the adjacency matrix of the graph that are closest to a value determined by the parameters of the model. It then applies $k$-means clustering to the embedding. We prove weak consistency and show that a simple local refinement step ensures strong consistency. A key ingredient is an application of a non-standard version of Davis-Kahan theorem to control eigenspace perturbations when eigenvalues are not simple. We also analyze the limiting spectrum of the adjacency matrix, using a combination of combinatorial and matrix techniques.
title Multi-Community Spectral Clustering for Geometric Graphs
topic Social and Information Networks
Machine Learning
Probability
Spectral Theory
url https://arxiv.org/abs/2508.00893