A Characterization of Lines in Finite Lie Incidence Geometries of Classical Type

Fuente: arXiv
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Autori principali: Busch, Sira, Van Maldeghem, Hendrik
Natura: Preprint
Pubblicazione: 2024
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author Busch, Sira
Van Maldeghem, Hendrik
author_facet Busch, Sira
Van Maldeghem, Hendrik
contents We consider any classical Grassmannian geometry $Γ$; that is, any projective or polar Grassmann space. Suppose every line in $Γ$ contains $s+1$ points. Then we classify all sets of points in $Γ$ of cardinality $s+1$, with the property, that no object of opposite type in the corresponding building, is opposite every point of the set. It turns out that such sets are either lines, or hyperbolic lines in symplectic residues, or ovoids in large symplectic subquadrangles of rank 2 residues in characteristic 2. This is a far-reaching extension of a famous and fundamental result of Bose & Burton from the 1960s. We describe a new way to classify geometric lines in finite classical geometries and how our results correspond to blocking sets.
format Preprint
id arxiv_https___arxiv_org_abs_2408_02413
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Characterization of Lines in Finite Lie Incidence Geometries of Classical Type
Busch, Sira
Van Maldeghem, Hendrik
Combinatorics
51E24 (Primary) 51A05, 51A50 (Secondary)
We consider any classical Grassmannian geometry $Γ$; that is, any projective or polar Grassmann space. Suppose every line in $Γ$ contains $s+1$ points. Then we classify all sets of points in $Γ$ of cardinality $s+1$, with the property, that no object of opposite type in the corresponding building, is opposite every point of the set. It turns out that such sets are either lines, or hyperbolic lines in symplectic residues, or ovoids in large symplectic subquadrangles of rank 2 residues in characteristic 2. This is a far-reaching extension of a famous and fundamental result of Bose & Burton from the 1960s. We describe a new way to classify geometric lines in finite classical geometries and how our results correspond to blocking sets.
title A Characterization of Lines in Finite Lie Incidence Geometries of Classical Type
topic Combinatorics
51E24 (Primary) 51A05, 51A50 (Secondary)
url https://arxiv.org/abs/2408.02413