Improved Directed Expander Decompositions

Fuente: arXiv
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Autores principales: Fleischmann, Henry, Li, George Z., Li, Jason
Formato: Preprint
Publicado: 2025
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author Fleischmann, Henry
Li, George Z.
Li, Jason
author_facet Fleischmann, Henry
Li, George Z.
Li, Jason
contents We obtain faster expander decomposition algorithms for directed graphs, matching the guarantees of Saranurak and Wang (SODA 2019) for expander decomposition on undirected graphs. Our algorithms are faster than prior work and also generalize almost losslessly to capacitated graphs. In particular, we obtain the first directed expander decomposition algorithm for capacitated graphs in near-linear time with optimal dependence on $ϕ$. To obtain our result, we provide the first implementation and analysis of the non-stop cut-matching game for directed, capacitated graphs. All existing directed expander decomposition algorithms instead temporarily add ''fake edges'' before pruning them away in a final cleanup step. Our result shows that the natural undirected approach applies even to directed graphs. The difficulty is in its analysis, which is technical and requires significant modifications from the original setting of undirected graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09729
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Improved Directed Expander Decompositions
Fleischmann, Henry
Li, George Z.
Li, Jason
Data Structures and Algorithms
We obtain faster expander decomposition algorithms for directed graphs, matching the guarantees of Saranurak and Wang (SODA 2019) for expander decomposition on undirected graphs. Our algorithms are faster than prior work and also generalize almost losslessly to capacitated graphs. In particular, we obtain the first directed expander decomposition algorithm for capacitated graphs in near-linear time with optimal dependence on $ϕ$. To obtain our result, we provide the first implementation and analysis of the non-stop cut-matching game for directed, capacitated graphs. All existing directed expander decomposition algorithms instead temporarily add ''fake edges'' before pruning them away in a final cleanup step. Our result shows that the natural undirected approach applies even to directed graphs. The difficulty is in its analysis, which is technical and requires significant modifications from the original setting of undirected graphs.
title Improved Directed Expander Decompositions
topic Data Structures and Algorithms
url https://arxiv.org/abs/2507.09729