Automorphisms of Lie incidence geometries with spectral gaps

Fuente: arXiv
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Hauptverfasser: Neyt, Yannick, Parkinson, James, Van Maldeghem, Hendrik
Format: Preprint
Veröffentlicht: 2025
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author Neyt, Yannick
Parkinson, James
Van Maldeghem, Hendrik
author_facet Neyt, Yannick
Parkinson, James
Van Maldeghem, Hendrik
contents An automorphism of a building is called uniclass if the Weyl distance between any chamber and its image lies in a unique (twisted) conjugacy class of the Coxeter group. In a previous paper we characterised uniclass automorphisms of spherical buildings in terms of their fixed structure. In the present paper we restrict to the simply laced case and characterise uniclass automorphisms in terms of a spectral gap property. More precisely, we show that an automorphism of a thick irreducible spherical building of simply laced type is uniclass if and only if no point of the long root subgroup geometry is mapped to distance $1$ or codistance $1$.
format Preprint
id arxiv_https___arxiv_org_abs_2511_01119
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Automorphisms of Lie incidence geometries with spectral gaps
Neyt, Yannick
Parkinson, James
Van Maldeghem, Hendrik
Group Theory
An automorphism of a building is called uniclass if the Weyl distance between any chamber and its image lies in a unique (twisted) conjugacy class of the Coxeter group. In a previous paper we characterised uniclass automorphisms of spherical buildings in terms of their fixed structure. In the present paper we restrict to the simply laced case and characterise uniclass automorphisms in terms of a spectral gap property. More precisely, we show that an automorphism of a thick irreducible spherical building of simply laced type is uniclass if and only if no point of the long root subgroup geometry is mapped to distance $1$ or codistance $1$.
title Automorphisms of Lie incidence geometries with spectral gaps
topic Group Theory
url https://arxiv.org/abs/2511.01119