Abstract
We prove an affine analog of Scharlau’s reduction theorem for spherical buildings. To be a bit more precise let X be a euclidean building with spherical building \(\partial X\) at infinity. Then there exists a euclidean building \(\bar{X}\) such that X splits as a product of \(\bar{X}\) with some euclidean k-space such that \(\partial \bar{X}\) is the thick reduction of \(\partial X\) in the sense of Scharlau. In addition we prove a converse statement saying that an embedding of a thick spherical building at infinity extends to an embedding of the euclidean building having the extended spherical building as its boundary.
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We would like to thank the anonymous referee for many helpful comments and suggestions. The first author would like to thank Misha Kapovich for helpful discussions.
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Schwer, P., Weniger, D. A structure theorem for euclidean buildings. J. Geom. 110, 18 (2019). https://doi.org/10.1007/s00022-019-0473-3
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DOI: https://doi.org/10.1007/s00022-019-0473-3