Most plane curves over finite fields are not blocking

Fuente: arXiv
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Hauptverfasser: Asgarli, Shamil, Ghioca, Dragos, Yip, Chi Hoi
Format: Preprint
Veröffentlicht: 2022
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author Asgarli, Shamil
Ghioca, Dragos
Yip, Chi Hoi
author_facet Asgarli, Shamil
Ghioca, Dragos
Yip, Chi Hoi
contents A plane curve $C\subset\mathbb{P}^2$ of degree $d$ is called \emph{blocking} if every $\mathbb{F}_q$-line in the plane meets $C$ at some $\mathbb{F}_q$-point. We prove that the proportion of blocking curves among those of degree $d$ is $o(1)$ when $d\geq 2q-1$ and $q \to \infty$. We also show that the same conclusion holds for smooth curves under the somewhat weaker condition $d\geq 3p$ and $d, q \to \infty$. Moreover, the two events in which a random plane curve is smooth and respectively blocking are shown to be asymptotically independent. Extending a classical result on the number of $\mathbb{F}_q$-roots of random polynomials, we find that the limiting distribution of the number of $\mathbb{F}_q$-points in the intersection of a random plane curve and a fixed $\mathbb{F}_q$-line is Poisson with mean $1$. We also present an explicit formula for the proportion of blocking curves involving statistics on the number of $\mathbb{F}_q$-points contained in a union of $k$ lines for $k=1, 2, \ldots, q^2+q+1$.
format Preprint
id arxiv_https___arxiv_org_abs_2211_08523
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Most plane curves over finite fields are not blocking
Asgarli, Shamil
Ghioca, Dragos
Yip, Chi Hoi
Algebraic Geometry
Combinatorics
Number Theory
Primary: 14H50, 51E21, Secondary: 11G20, 11T55, 14N10, 05B25
A plane curve $C\subset\mathbb{P}^2$ of degree $d$ is called \emph{blocking} if every $\mathbb{F}_q$-line in the plane meets $C$ at some $\mathbb{F}_q$-point. We prove that the proportion of blocking curves among those of degree $d$ is $o(1)$ when $d\geq 2q-1$ and $q \to \infty$. We also show that the same conclusion holds for smooth curves under the somewhat weaker condition $d\geq 3p$ and $d, q \to \infty$. Moreover, the two events in which a random plane curve is smooth and respectively blocking are shown to be asymptotically independent. Extending a classical result on the number of $\mathbb{F}_q$-roots of random polynomials, we find that the limiting distribution of the number of $\mathbb{F}_q$-points in the intersection of a random plane curve and a fixed $\mathbb{F}_q$-line is Poisson with mean $1$. We also present an explicit formula for the proportion of blocking curves involving statistics on the number of $\mathbb{F}_q$-points contained in a union of $k$ lines for $k=1, 2, \ldots, q^2+q+1$.
title Most plane curves over finite fields are not blocking
topic Algebraic Geometry
Combinatorics
Number Theory
Primary: 14H50, 51E21, Secondary: 11G20, 11T55, 14N10, 05B25
url https://arxiv.org/abs/2211.08523