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

2024/04/08 by Sam Mattheus, Mattheus, Sam, Geertrui Van de Voorde +1
Engineering · #Combinatorics (math.CO) #FOS: Mathematics #Optimization and Packing Problems

paper · pdf · doi:10.48550/arxiv.2404.05305

openalex publication_date 2024/04/08 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

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 PG(2r-1,q) and plane spreads in PG(5,q), and caps in 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 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.

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