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Some remarks on proper actions, proper metric spaces, and buildings

  • Linus Kramer EMAIL logo
Published/Copyright: October 19, 2022
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Abstract

We discuss various aspects of isometric group actions on proper metric spaces. As one application, we show that a proper and Weyl transitive action on a euclidean building is strongly transitive on the maximal atlas (the complete apartment system) of the building.

MSC 2010: 54H15; 20E42

Dedicated to the memory of Helmut Reiner Salzmann


Funding statement: Funded by the Deutsche Forschungsgemeinschaft through a Polish-German Beethoven grant KR1668/11, and under Germany’s Excellence Strategy EXC 2044-390685587, Mathematics Münster: Dynamics-Geometry-Structure.

  1. Communicated by: R. Weiss

Acknowledgements

Arthur Bartels’ request for a solid reference for Theorem 5.19 initiated a first, three page version of the present article. I thank Bertrand Rémy and Guy Rousseau for some remarks on Bruhat–Tits buildings. Stefan Witzel, Herbert Abels and Polychronis Strantzalos spotted mistakes and pointed out some more references. In particular, the authors kindly informed me that the forthcoming book [2] will contain the results that we present in Section 2. Richard Weiss made helpful comments on the proof of Theorem 5.19 and the material surrounding it. Philip Möller read the article, spotted several mistakes and made many good suggestions. I would also like to thank the referee, who raised several very good questions about an earlier version of the manuscript.

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Received: 2021-12-01
Revised: 2022-05-09
Published Online: 2022-10-19
Published in Print: 2022-10-26

© 2022 Walter de Gruyter GmbH, Berlin/Boston

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