Unavoidable Minors of Matroids with Minimum Cocircuit Size Four

Fuente: arXiv
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Autores principales: Mizell, Matthew, Oxley, James
Formato: Preprint
Publicado: 2025
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author Mizell, Matthew
Oxley, James
author_facet Mizell, Matthew
Oxley, James
contents In 1963, Halin and Jung proved that every simple graph with minimum degree at least four has $K_5$ or $K_{2,2,2}$ as a minor. Mills and Turner proved an analog of this theorem by showing that every $3$-connected binary matroid in which every cocircuit has size at least four has $F_7, M^*(K_{3,3}), M(K_5),$ or $ M(K_{2,2,2})$ as a minor. Generalizing these results, this paper proves that every simple matroid in which all cocircuits have at least four elements has as a minor one of nine matroids, seven of which are well known. All nine of these special matroids have rank at most five and have at most twelve elements.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09015
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unavoidable Minors of Matroids with Minimum Cocircuit Size Four
Mizell, Matthew
Oxley, James
Combinatorics
In 1963, Halin and Jung proved that every simple graph with minimum degree at least four has $K_5$ or $K_{2,2,2}$ as a minor. Mills and Turner proved an analog of this theorem by showing that every $3$-connected binary matroid in which every cocircuit has size at least four has $F_7, M^*(K_{3,3}), M(K_5),$ or $ M(K_{2,2,2})$ as a minor. Generalizing these results, this paper proves that every simple matroid in which all cocircuits have at least four elements has as a minor one of nine matroids, seven of which are well known. All nine of these special matroids have rank at most five and have at most twelve elements.
title Unavoidable Minors of Matroids with Minimum Cocircuit Size Four
topic Combinatorics
url https://arxiv.org/abs/2507.09015