Excluding an induced wheel minor in graphs without large induced stars

Fuente: arXiv
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Main Authors: Choi, Mujin, Hilaire, Claire, Milanič, Martin, Wiederrecht, Sebastian
Format: Preprint
Published: 2025
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author Choi, Mujin
Hilaire, Claire
Milanič, Martin
Wiederrecht, Sebastian
author_facet Choi, Mujin
Hilaire, Claire
Milanič, Martin
Wiederrecht, Sebastian
contents We study a conjecture due to Dallard, Krnc, Kwon, Milanič, Munaro, Štorgel, and Wiederrecht stating that for any positive integer $d$ and any planar graph $H$, the class of all $K_{1,d}$-free graphs without $H$ as an induced minor has bounded tree-independence number. A $k$-wheel is the graph obtained from a cycle of length $k$ by adding a vertex adjacent to all vertices of the cycle. We show that the conjecture of Dallard et al. is true when $H$ is a $k$-wheel for any $k\geq 3$. Our proof uses a generalization of the concept of brambles to tree-independence number. As a consequence of our main result, several important $\mathsf{NP}$-hard problems such as Maximum Independent Set are tractable on $K_{1,d}$-free graphs without large induced wheel minors. Moreover, for fixed $d$ and $k$, we provide a polynomial-time algorithm that, given a $K_{1,d}$-free graph $G$ as input, finds an induced minor model of a $k$-wheel in $G$ if one exists.
format Preprint
id arxiv_https___arxiv_org_abs_2506_08829
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Excluding an induced wheel minor in graphs without large induced stars
Choi, Mujin
Hilaire, Claire
Milanič, Martin
Wiederrecht, Sebastian
Combinatorics
Discrete Mathematics
Data Structures and Algorithms
05C75 (Primary), 05C83, 05C69, 05C05, 05C85 (Secondary)
We study a conjecture due to Dallard, Krnc, Kwon, Milanič, Munaro, Štorgel, and Wiederrecht stating that for any positive integer $d$ and any planar graph $H$, the class of all $K_{1,d}$-free graphs without $H$ as an induced minor has bounded tree-independence number. A $k$-wheel is the graph obtained from a cycle of length $k$ by adding a vertex adjacent to all vertices of the cycle. We show that the conjecture of Dallard et al. is true when $H$ is a $k$-wheel for any $k\geq 3$. Our proof uses a generalization of the concept of brambles to tree-independence number. As a consequence of our main result, several important $\mathsf{NP}$-hard problems such as Maximum Independent Set are tractable on $K_{1,d}$-free graphs without large induced wheel minors. Moreover, for fixed $d$ and $k$, we provide a polynomial-time algorithm that, given a $K_{1,d}$-free graph $G$ as input, finds an induced minor model of a $k$-wheel in $G$ if one exists.
title Excluding an induced wheel minor in graphs without large induced stars
topic Combinatorics
Discrete Mathematics
Data Structures and Algorithms
05C75 (Primary), 05C83, 05C69, 05C05, 05C85 (Secondary)
url https://arxiv.org/abs/2506.08829