Webs and squabs of conics over finite fields

Fuente: arXiv
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Main Authors: Alnajjarine, Nour, Lavrauw, Michel
Format: Preprint
Published: 2024
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author Alnajjarine, Nour
Lavrauw, Michel
author_facet Alnajjarine, Nour
Lavrauw, Michel
contents This paper is a contribution towards a solution for the longstanding open problem of classifying linear systems of conics over finite fields initiated by L. E. Dickson in 1908, through his study of the projective equivalence classes of pencils of conics in $\mathrm{PG}(2,q)$, for $q$ odd. In this paper a set of complete invariants is determined for the projective equivalence classes of webs and of squabs of conics in $\mathrm{PG}(2,q)$, both for $q$ odd and even. Our approach is mainly geometric, and involves a comprehensive study of the geometric and combinatorial properties of the Veronese surface in $\mathrm{PG}(5,q)$. The main contribution is the determination of the distribution of the different types of hyperplanes incident with the $K$-orbit representatives of points and lines of $\mathrm{PG}(5,q)$, where $K\cong\mathrm{PGL}(3,q)$, is the subgroup of $\mathrm{PGL}(6,q)$ stabilizing the Veronese surface.
format Preprint
id arxiv_https___arxiv_org_abs_2405_10710
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Webs and squabs of conics over finite fields
Alnajjarine, Nour
Lavrauw, Michel
Combinatorics
Algebraic Geometry
This paper is a contribution towards a solution for the longstanding open problem of classifying linear systems of conics over finite fields initiated by L. E. Dickson in 1908, through his study of the projective equivalence classes of pencils of conics in $\mathrm{PG}(2,q)$, for $q$ odd. In this paper a set of complete invariants is determined for the projective equivalence classes of webs and of squabs of conics in $\mathrm{PG}(2,q)$, both for $q$ odd and even. Our approach is mainly geometric, and involves a comprehensive study of the geometric and combinatorial properties of the Veronese surface in $\mathrm{PG}(5,q)$. The main contribution is the determination of the distribution of the different types of hyperplanes incident with the $K$-orbit representatives of points and lines of $\mathrm{PG}(5,q)$, where $K\cong\mathrm{PGL}(3,q)$, is the subgroup of $\mathrm{PGL}(6,q)$ stabilizing the Veronese surface.
title Webs and squabs of conics over finite fields
topic Combinatorics
Algebraic Geometry
url https://arxiv.org/abs/2405.10710