Acyclic Edge Coloring of 3-sparse Graphs

Fuente: arXiv
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Hauptverfasser: Anto, Nevil, Basavaraju, Manu, Kulamarva, Shashanka
Format: Preprint
Veröffentlicht: 2025
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author Anto, Nevil
Basavaraju, Manu
Kulamarva, Shashanka
author_facet Anto, Nevil
Basavaraju, Manu
Kulamarva, Shashanka
contents A proper edge coloring of a graph without any bichromatic cycles is said to be an acyclic edge coloring of the graph. The acyclic chromatic index of a graph $G$ denoted by $a'(G)$, is the minimum integer $k$ such that $G$ has an acyclic edge coloring with $k$ colors. Fiamč\'ık conjectured that for a graph $G$ with maximum degree $Δ$, $a'(G) \le Δ+2$. A graph $G$ is said to be $3$-sparse if every edge in $G$ is incident on at least one vertex of degree at most $3$. We prove the conjecture for the class of $3$-sparse graphs. Further, we give a stronger bound of $Δ+1$, if there exists an edge $xy$ in the graph with $d_G(x)+ d_G(y) < Δ+3$. When $ Δ> 3$, the $3$-sparse graphs where no such edge exists is the set of bipartite graphs where one partition has vertices with degree exactly $3$ and the other partition has vertices with degree exactly $Δ$.
format Preprint
id arxiv_https___arxiv_org_abs_2501_11281
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Acyclic Edge Coloring of 3-sparse Graphs
Anto, Nevil
Basavaraju, Manu
Kulamarva, Shashanka
Combinatorics
Discrete Mathematics
05C15
A proper edge coloring of a graph without any bichromatic cycles is said to be an acyclic edge coloring of the graph. The acyclic chromatic index of a graph $G$ denoted by $a'(G)$, is the minimum integer $k$ such that $G$ has an acyclic edge coloring with $k$ colors. Fiamč\'ık conjectured that for a graph $G$ with maximum degree $Δ$, $a'(G) \le Δ+2$. A graph $G$ is said to be $3$-sparse if every edge in $G$ is incident on at least one vertex of degree at most $3$. We prove the conjecture for the class of $3$-sparse graphs. Further, we give a stronger bound of $Δ+1$, if there exists an edge $xy$ in the graph with $d_G(x)+ d_G(y) < Δ+3$. When $ Δ> 3$, the $3$-sparse graphs where no such edge exists is the set of bipartite graphs where one partition has vertices with degree exactly $3$ and the other partition has vertices with degree exactly $Δ$.
title Acyclic Edge Coloring of 3-sparse Graphs
topic Combinatorics
Discrete Mathematics
05C15
url https://arxiv.org/abs/2501.11281