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Abstract

Whether or not the Sparsest Cut problem admits an efficient \(O(1)\)-approximation algorithm is a fundamental algorithmic question with connections to geometry and the Unique Games Conjecture. We design an \(O(1)\)-approximation algorithm to Sparsest Cut for the class of Cayley graphs over Abelian groups, running in time \(n^{O(1)}\cdot \exp\{d^{O(d)}\}\) where \(d\) is the degree of the graph. Previous work has centered on solving cut problems on graphs which are ``expander-like'' in various senses, such as being a small-set expander or having low threshold rank. In contrast, low-degree Abelian Cayley graphs are natural examples of non-expanding graphs far from these assumptions (e.g. the cycle). We demonstrate that spectral and semidefinite programming-based methods can still succeed in these graphs by analyzing an eigenspace enumeration algorithm which searches for a sparse cut among the low eigenspace of the Laplacian matrix. We dually interpret this algorithm as searching for a hyperplane cut in a low-dimensional embedding of the graph. In order to analyze the algorithm, we prove a bound of \(d^{O(d)}\) on the number of eigenvalues ``near'' \(\lambda_2\) for connected degree-\(d\) Abelian Cayley graphs. We obtain a tight bound of \(2^{\Theta(d)}\) on the multiplicity of \(\lambda_2\) itself which improves on a previous bound of \(2^{O(d^2)}\) by Lee and Makarychev.

Details

1009240
Title
Sparsest cut and eigenvalue multiplicities on low degree Abelian Cayley graphs
Publication title
arXiv.org; Ithaca
Publication year
2024
Publication date
Dec 22, 2024
Section
Computer Science; Mathematics
Publisher
Cornell University Library, arXiv.org
Source
arXiv.org
Place of publication
Ithaca
Country of publication
United States
University/institution
Cornell University Library arXiv.org
e-ISSN
2331-8422
Source type
Working Paper
Language of publication
English
Document type
Working Paper
Publication history
 
 
Online publication date
2024-12-24
Milestone dates
2024-12-22 (Submission v1)
Publication history
 
 
   First posting date
24 Dec 2024
ProQuest document ID
3148979714
Document URL
https://www.proquest.com/working-papers/sparsest-cut-eigenvalue-multiplicities-on-low/docview/3148979714/se-2?accountid=208611
Full text outside of ProQuest
Copyright
© 2024. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.
Last updated
2024-12-25
Database
2 databases
  • ProQuest One Academic
  • ProQuest One Academic