On decomposition thresholds for odd-length cycles and other tripartite graphs

Fuente: arXiv
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Autori principali: Bryant, Darryn, Dukes, Peter, Horsley, Daniel, Maenhaut, Barbara, Montgomery, Richard
Natura: Preprint
Pubblicazione: 2024
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author Bryant, Darryn
Dukes, Peter
Horsley, Daniel
Maenhaut, Barbara
Montgomery, Richard
author_facet Bryant, Darryn
Dukes, Peter
Horsley, Daniel
Maenhaut, Barbara
Montgomery, Richard
contents An (edge) decomposition of a graph $G$ is a set of subgraphs of $G$ whose edge sets partition the edge set of $G$. Here we show, for each odd $\ell \geq 5$, that any graph $G$ of sufficiently large order $n$ with minimum degree at least $(\frac{1}{2}+\frac{1}{2\ell-4}+o(1))n$ has a decomposition into $\ell$-cycles if and only if $\ell$ divides $|E(G)|$ and each vertex of $G$ has even degree. This threshold cannot be improved beyond $\frac{1}{2}+\frac{1}{2\ell-2}$. It was previously shown that the thresholds approach $\frac{1}{2}$ as $\ell$ becomes large, but our thresholds do so significantly more rapidly. Our methods can be applied to tripartite graphs more generally and we also obtain some bounds for decomposition thresholds of other tripartite graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2411_17232
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On decomposition thresholds for odd-length cycles and other tripartite graphs
Bryant, Darryn
Dukes, Peter
Horsley, Daniel
Maenhaut, Barbara
Montgomery, Richard
Combinatorics
05C51 (Primary) 05C70 (Secondary)
An (edge) decomposition of a graph $G$ is a set of subgraphs of $G$ whose edge sets partition the edge set of $G$. Here we show, for each odd $\ell \geq 5$, that any graph $G$ of sufficiently large order $n$ with minimum degree at least $(\frac{1}{2}+\frac{1}{2\ell-4}+o(1))n$ has a decomposition into $\ell$-cycles if and only if $\ell$ divides $|E(G)|$ and each vertex of $G$ has even degree. This threshold cannot be improved beyond $\frac{1}{2}+\frac{1}{2\ell-2}$. It was previously shown that the thresholds approach $\frac{1}{2}$ as $\ell$ becomes large, but our thresholds do so significantly more rapidly. Our methods can be applied to tripartite graphs more generally and we also obtain some bounds for decomposition thresholds of other tripartite graphs.
title On decomposition thresholds for odd-length cycles and other tripartite graphs
topic Combinatorics
05C51 (Primary) 05C70 (Secondary)
url https://arxiv.org/abs/2411.17232