An improvement on the bound for the acyclic chromatic index

Fuente: arXiv
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Main Authors: Kirousis, Lefteris, Livieratos, John, Singh, Alexandros
Format: Preprint
Published: 2026
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author Kirousis, Lefteris
Livieratos, John
Singh, Alexandros
author_facet Kirousis, Lefteris
Livieratos, John
Singh, Alexandros
contents The acyclic chromatic index (or acyclic edge-chromatic number) of a graph is the least number of colors needed to properly color its edges so that none of its cycles has only two colors. We show that for a graph of max degree $Δ$, the acyclic chromatic index is at most $3.142(Δ-1)+1$, improving on the (best to date) bound of Fialho et al. (2020). Our improvement is made possible by considering unordered (non-plane) trees, instead of ordered (plane) ones, as witness structures for the Lovász Local Lemma, a key combinatorial tool often used in related works. The counting of these witness structures entails methods of Analytic Combinatorics.
format Preprint
id arxiv_https___arxiv_org_abs_2602_14859
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle An improvement on the bound for the acyclic chromatic index
Kirousis, Lefteris
Livieratos, John
Singh, Alexandros
Combinatorics
Discrete Mathematics
The acyclic chromatic index (or acyclic edge-chromatic number) of a graph is the least number of colors needed to properly color its edges so that none of its cycles has only two colors. We show that for a graph of max degree $Δ$, the acyclic chromatic index is at most $3.142(Δ-1)+1$, improving on the (best to date) bound of Fialho et al. (2020). Our improvement is made possible by considering unordered (non-plane) trees, instead of ordered (plane) ones, as witness structures for the Lovász Local Lemma, a key combinatorial tool often used in related works. The counting of these witness structures entails methods of Analytic Combinatorics.
title An improvement on the bound for the acyclic chromatic index
topic Combinatorics
Discrete Mathematics
url https://arxiv.org/abs/2602.14859