Minors of matroids represented by sparse random matrices over finite fields

Fuente: arXiv
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Autores principales: Gao, Pu, Nelson, Peter
Formato: Preprint
Publicado: 2023
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author Gao, Pu
Nelson, Peter
author_facet Gao, Pu
Nelson, Peter
contents Consider a random $n\times m$ matrix $A$ over the finite field of order $q$ where every column has precisely $k$ nonzero elements, and let $M[A]$ be the matroid represented by $A$. In the case that q=2, Cooper, Frieze and Pegden (RS\&A 2019) proved that given a fixed binary matroid $N$, if $k\ge k_N$ and $m/n\ge d_N$ where $k_N$ and $d_N$ are sufficiently large constants depending on N, then a.a.s. $M[A]$ contains $N$ as a minor. We improve their result by determining the sharp threshold (of $m/n$) for the appearance of a fixed matroid $N$ as a minor of $M[A]$, for every $k\ge 3$, and every finite field.
format Preprint
id arxiv_https___arxiv_org_abs_2307_15685
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Minors of matroids represented by sparse random matrices over finite fields
Gao, Pu
Nelson, Peter
Combinatorics
Consider a random $n\times m$ matrix $A$ over the finite field of order $q$ where every column has precisely $k$ nonzero elements, and let $M[A]$ be the matroid represented by $A$. In the case that q=2, Cooper, Frieze and Pegden (RS\&A 2019) proved that given a fixed binary matroid $N$, if $k\ge k_N$ and $m/n\ge d_N$ where $k_N$ and $d_N$ are sufficiently large constants depending on N, then a.a.s. $M[A]$ contains $N$ as a minor. We improve their result by determining the sharp threshold (of $m/n$) for the appearance of a fixed matroid $N$ as a minor of $M[A]$, for every $k\ge 3$, and every finite field.
title Minors of matroids represented by sparse random matrices over finite fields
topic Combinatorics
url https://arxiv.org/abs/2307.15685