Improved girth approximation in weighted undirected graphs

Fuente: arXiv
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Main Authors: Kadria, Avi, Roditty, Liam, Sidford, Aaron, Williams, Virginia Vassilevska, Zwick, Uri
Format: Preprint
Published: 2025
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author Kadria, Avi
Roditty, Liam
Sidford, Aaron
Williams, Virginia Vassilevska
Zwick, Uri
author_facet Kadria, Avi
Roditty, Liam
Sidford, Aaron
Williams, Virginia Vassilevska
Zwick, Uri
contents Let $G = (V,E,\ell)$ be a $n$-node $m$-edge weighted undirected graph, where $\ell: E \rightarrow (0,\infty)$ is a real \emph{length} function defined on its edges, and let $g$ denote the girth of $G$, i.e., the length of its shortest cycle. We present an algorithm that, for any input, integer $k \geq 1$, in $O(kn^{1+1/k}\log{n} + m(k+\log{n}))$ expected time finds a cycle of length at most $\frac{4k}{3}g$. This algorithm nearly matches a $O(n^{1+1/k}\log{n})$-time algorithm of \cite{KadriaRSWZ22} which applied to unweighted graphs of girth $3$. For weighted graphs, this result also improves upon the previous state-of-the-art algorithm that in $O((n^{1+1/k}\log n+m)\log (nM))$ time, where $\ell: E \rightarrow [1, M]$ is an integral length function, finds a cycle of length at most $2kg$~\cite{KadriaRSWZ22}. For $k=1$ this result improves upon the result of Roditty and Tov~\cite{RodittyT13}.
format Preprint
id arxiv_https___arxiv_org_abs_2507_13869
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Improved girth approximation in weighted undirected graphs
Kadria, Avi
Roditty, Liam
Sidford, Aaron
Williams, Virginia Vassilevska
Zwick, Uri
Data Structures and Algorithms
Let $G = (V,E,\ell)$ be a $n$-node $m$-edge weighted undirected graph, where $\ell: E \rightarrow (0,\infty)$ is a real \emph{length} function defined on its edges, and let $g$ denote the girth of $G$, i.e., the length of its shortest cycle. We present an algorithm that, for any input, integer $k \geq 1$, in $O(kn^{1+1/k}\log{n} + m(k+\log{n}))$ expected time finds a cycle of length at most $\frac{4k}{3}g$. This algorithm nearly matches a $O(n^{1+1/k}\log{n})$-time algorithm of \cite{KadriaRSWZ22} which applied to unweighted graphs of girth $3$. For weighted graphs, this result also improves upon the previous state-of-the-art algorithm that in $O((n^{1+1/k}\log n+m)\log (nM))$ time, where $\ell: E \rightarrow [1, M]$ is an integral length function, finds a cycle of length at most $2kg$~\cite{KadriaRSWZ22}. For $k=1$ this result improves upon the result of Roditty and Tov~\cite{RodittyT13}.
title Improved girth approximation in weighted undirected graphs
topic Data Structures and Algorithms
url https://arxiv.org/abs/2507.13869