New bounds for linear arboricity and related problems

Fuente: arXiv
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Main Authors: Christoph, Micha, Draganić, Nemanja, Girão, António, Hurley, Eoin, Michel, Lukas, Müyesser, Alp
Format: Preprint
Published: 2025
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author Christoph, Micha
Draganić, Nemanja
Girão, António
Hurley, Eoin
Michel, Lukas
Müyesser, Alp
author_facet Christoph, Micha
Draganić, Nemanja
Girão, António
Hurley, Eoin
Michel, Lukas
Müyesser, Alp
contents A linear forest is a collection of vertex-disjoint paths. The Linear Arboricity Conjecture states that every graph of maximum degree $Δ$ can be decomposed into at most $\lceil(Δ+1)/2\rceil$ linear forests. We prove that $Δ/2 + \mathcal{O}(\log n)$ linear forests suffice, where $n$ is the number of vertices of the graph. If $Δ= Ω(n^\varepsilon)$, this is an exponential improvement over the previous best error term. We achieve this by generalising Pósa rotations from rotations of one endpoint of a path to simultaneous rotations of multiple endpoints of a linear forest. This method has further applications, including the resolution of a conjecture of Feige and Fuchs on spanning linear forests with few paths and the existence of optimally short tours in connected regular graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2507_20500
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle New bounds for linear arboricity and related problems
Christoph, Micha
Draganić, Nemanja
Girão, António
Hurley, Eoin
Michel, Lukas
Müyesser, Alp
Combinatorics
A linear forest is a collection of vertex-disjoint paths. The Linear Arboricity Conjecture states that every graph of maximum degree $Δ$ can be decomposed into at most $\lceil(Δ+1)/2\rceil$ linear forests. We prove that $Δ/2 + \mathcal{O}(\log n)$ linear forests suffice, where $n$ is the number of vertices of the graph. If $Δ= Ω(n^\varepsilon)$, this is an exponential improvement over the previous best error term. We achieve this by generalising Pósa rotations from rotations of one endpoint of a path to simultaneous rotations of multiple endpoints of a linear forest. This method has further applications, including the resolution of a conjecture of Feige and Fuchs on spanning linear forests with few paths and the existence of optimally short tours in connected regular graphs.
title New bounds for linear arboricity and related problems
topic Combinatorics
url https://arxiv.org/abs/2507.20500