Upper bounds for the number of substructures in finite geometries from the container method

Fuente: arXiv
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Auteurs principaux: Mattheus, Sam, Van de Voorde, Geertrui
Format: Preprint
Publié: 2024
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author Mattheus, Sam
Van de Voorde, Geertrui
author_facet Mattheus, Sam
Van de Voorde, Geertrui
contents We use techniques from algebraic and extremal combinatorics to derive upper bounds on the number of independent sets in several (hyper)graphs arising from finite geometry. In this way, we obtain asymptotically sharp upper bounds for partial ovoids and EKR-sets of flags in polar spaces, line spreads in $\mathrm{PG}(2r-1,q)$ and plane spreads in $\mathrm{PG}(5,q)$, and caps in $\mathrm{PG}(3,q)$. The latter result extends work due to Roche-Newton and Warren and Bhowmick and Roche-Newton. Finally, we investigate caps in $p$-random subsets of $\mathrm{PG}(r,q)$, which parallels recent work for arcs in projective planes by Bhowmick and Roche-Newton, and by Roche-Newton and Warren, and arcs in projective spaces by Chen, Liu, Nie and Zeng.
format Preprint
id arxiv_https___arxiv_org_abs_2404_05305
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Upper bounds for the number of substructures in finite geometries from the container method
Mattheus, Sam
Van de Voorde, Geertrui
Combinatorics
We use techniques from algebraic and extremal combinatorics to derive upper bounds on the number of independent sets in several (hyper)graphs arising from finite geometry. In this way, we obtain asymptotically sharp upper bounds for partial ovoids and EKR-sets of flags in polar spaces, line spreads in $\mathrm{PG}(2r-1,q)$ and plane spreads in $\mathrm{PG}(5,q)$, and caps in $\mathrm{PG}(3,q)$. The latter result extends work due to Roche-Newton and Warren and Bhowmick and Roche-Newton. Finally, we investigate caps in $p$-random subsets of $\mathrm{PG}(r,q)$, which parallels recent work for arcs in projective planes by Bhowmick and Roche-Newton, and by Roche-Newton and Warren, and arcs in projective spaces by Chen, Liu, Nie and Zeng.
title Upper bounds for the number of substructures in finite geometries from the container method
topic Combinatorics
url https://arxiv.org/abs/2404.05305