Startseite Mathematik Kostant convexity for affine buildings
Artikel
Lizenziert
Nicht lizenziert Erfordert eine Authentifizierung

Kostant convexity for affine buildings

  • Petra Hitzelberger
Veröffentlicht/Copyright: 12. Februar 2010
Forum Mathematicum
Aus der Zeitschrift Band 22 Heft 5

Abstract

We prove an analogue of Kostant's convexity theorem for thick affine buildings and give an application for groups with affine BN-pairs. Recall that there are two natural retractions of the affine building onto a fixed apartment A: The retraction r centered at an alcove in A and the retraction ρ centered at a chamber in the spherical building at infinity. We prove that for each special vertex xA the set ρ(r–1(W .x)) is a certain convex hull of W .x. The proof can be reduced to a statement about Coxeter complexes and heavily relies on a character formula for highest weight representations of algebraic groups.

Received: 2008-03-12
Revised: 2009-03-02
Published Online: 2010-02-12
Published in Print: 2010-September

© de Gruyter 2010

Heruntergeladen am 4.2.2026 von https://www.degruyterbrill.com/document/doi/10.1515/forum.2010.051/pdf?lang=de
Button zum nach oben scrollen