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Let $\theta$ be an automorphism of a thick irreducible spherical building $\Delta$ of rank at least $3$ with no Fano plane residues. We prove that if there exist both type $J_1$ and $J_2$ simplices of $\Delta$ mapped onto opposite simplices…

Combinatorics · Mathematics 2018-09-10 J. Parkinson , H. Van Maldeghem

To each automorphism of a spherical building there is naturally associated an "opposition diagram", which encodes the types of the simplices of the building that are mapped onto opposite simplices. If no chamber (that is, no maximal…

Group Theory · Mathematics 2020-02-20 James Parkinson , Hendrik Van Maldeghem

An automorphism of a spherical building is called \textit{domestic} if it maps no chamber to an opposite chamber. In previous work the classification of domestic automorphisms in large spherical buildings of types $\mathsf{F}_4$,…

Group Theory · Mathematics 2025-04-22 James Parkinson , Hendrik Van Maldeghem

An automorphism of a spherical building is called \textit{domestic} if it maps no chamber onto an opposite chamber. This paper forms a significant part of a large project classifying domestic automorphisms of spherical buildings of…

Group Theory · Mathematics 2024-02-08 Yannick Neyt , James Parkinson , Hendrik Van Maldeghem , Magali Victoor

An automorphism of a spherical building is called domestic if it maps no chamber to an opposite chamber. In this paper we classify domestic automorphisms of spherical buildings of classical type.

Group Theory · Mathematics 2023-03-15 James Parkinson , Hendrik Van Maldeghem

We show that every automorphism of a thick twin building interchanging the halves of the building maps some residue to an opposite one. Furthermore we show that no automorphism of a locally finite 2-spherical twin building of rank at least…

Combinatorics · Mathematics 2012-03-29 Alice Devillers , James Parkinson , Hendrik Van Maldeghem

In this paper we introduce, for each closed orientable surface, an analogue of Tits buildings adjusted to investigation of the Torelli group of this surface. It is a simplicial complex with some additional structure. We call this complex…

Geometric Topology · Mathematics 2014-10-24 Benson Farb , Nikolai V. Ivanov

Suppose that \Delta, \Delta' are two buildings each arising from a semisimpe algebraic group over a field, a topological field in the former case, and that for both the buildings the Coxeter diagram has no isolated nodes. We give conditions…

Metric Geometry · Mathematics 2012-11-07 Rupert McCallum

Let $\Delta$ be a spherical building each of whose irreducible components is infinite, has rank at least 2 and satisfies the Moufang condition. We show that $\Delta$ can be given the structure of a topological building that is compact and…

Group Theory · Mathematics 2011-08-09 Theo Grundhofer , Linus Kramer , Hendrik Van Maldeghem , Richard M. Weiss

We classify the automorphisms of a Moufang hexagon mapping no chamber to an opposite chamber (such automorphisms are called domestic). This forms part of a larger program to classify domestic automorphisms of Moufang spherical buildings.

Group Theory · Mathematics 2022-12-26 James Parkinson , Hendrik Van Maldeghem

We offer a criterion for showing that the automorphism group of an ultrahomogeneous structure is topologically 2-generated and even has a cyclically dense conjugacy class. We then show how finite topological rank of the automorphism group…

Group Theory · Mathematics 2019-08-26 Itay Kaplan , Pierre Simon

Using the notion of a strongly regular hyperbolic automorphism of a locally finite Euclidean building, we prove that any (not necessarily discrete) closed, co-compact subgroup of the type-preserving automorphisms group of a locally finite…

Group Theory · Mathematics 2014-11-26 Corina Ciobotaru

If f is a nontrivial automorphism of a thick building Delta of purely infinite type, we prove that there is no bound on the distance that f moves a chamber. This has the following group-theoretic consequence: If G is a group of…

Group Theory · Mathematics 2007-10-09 Peter Abramenko , Kenneth S. Brown

We prove that every open subset of a euclidean building is a finite dimensional absolute neighborhood retract. This implies in particular that such a set has the homotopy type of a finite dimensional simplicial complex. We also include a…

Metric Geometry · Mathematics 2010-10-25 Linus Kramer

We give direct, geometric constructions for nontrivial root elations for rank $2$ residues of higher rank buildings $\Delta$ of type $\mathsf{B_n}, \mathsf{C_n}$ and $\mathsf{H_m}$ for $n \in \mathbb{N}$ and $m \in \{3,4\}$. We show that we…

Group Theory · Mathematics 2025-02-20 Sira Busch

We prove that if f is an orientation-preserving homeomorphism of a closed orientable surface M whose singular set is totally disconnected, then f is topologically conjugate to a conformal transformation.

Dynamical Systems · Mathematics 2019-01-03 Christian Bonatti , Boris Kolev

We prove that a convex subcomplex of a spherical building of type F4 or E6 is a subbuilding or the automorphisms of the subcomplex fix a point on it. Our approach is differential-geometric and based on the theory of metric spaces with…

Metric Geometry · Mathematics 2015-03-13 B. Leeb , C. Ramos-Cuevas

Frucht showed that, for any finite group $G$, there exists a cubic graph such that its automorphism group is isomorphic to $G$. For groups generated by two elements we simplify his construction to a graph with fewer nodes. In the general…

Group Theory · Mathematics 2023-07-25 Reymond Akpanya , Tom Goertzen

In this paper we study convex subcomplexes of spherical buildings. We pay special attention to fixed point sets of type-preserving isometries of spherical buildings. This sets are also convex subcomplexes of the natural polyhedral structure…

Metric Geometry · Mathematics 2014-08-14 Carlos Ramos-Cuevas

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…

Group Theory · Mathematics 2025-11-04 Yannick Neyt , James Parkinson , Hendrik Van Maldeghem
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