Cross ratios on boundaries of symmetric spaces and Euclidean buildings

We generalize the natural cross ratio on the ideal boundary of a rank one symmetric space, or even CAT(−1) space, to higher rank symmetric spaces and (nonlocally compact) Euclidean buildings. We obtain vector valued cross ratios defined on simplices of the building at infinity. We show several prope...

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Bibliographic Details
Main Author: Beyrer, Jonas (Author)
Format: Article (Journal)
Language:English
Published: 2021
In: Transformation groups
Year: 2021, Volume: 26, Issue: 1, Pages: 31-68
ISSN:1531-586X
DOI:10.1007/s00031-020-09549-5
Online Access:Verlag, kostenfrei, Volltext: https://doi.org/10.1007/s00031-020-09549-5
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Author Notes:J. Beyrer
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Summary:We generalize the natural cross ratio on the ideal boundary of a rank one symmetric space, or even CAT(−1) space, to higher rank symmetric spaces and (nonlocally compact) Euclidean buildings. We obtain vector valued cross ratios defined on simplices of the building at infinity. We show several properties of those cross ratios; for example that (under some restrictions) periods of hyperbolic isometries give back the translation vector. In addition, we show that cross ratio preserving maps on the chamber set are induced by isometries and vice versa, - motivating that the cross ratios bring the geometry of the symmetric space/Euclidean building to the boundary.
Item Description:Published: 29 January 2020
Gesehen am 12.08.2021
Physical Description:Online Resource
ISSN:1531-586X
DOI:10.1007/s00031-020-09549-5