3 papers
math.GR2026
Combinatorial Characterizations of Virtually Torsion-Free and Virtually Free Groups
R. Köhl, M. Reza Salarian
We establish combinatorial characterizations of virtually torsion-free and virtually free groups using the canonical graph decomposition theory in \cite{DJKK22}. Our main results s…
math.RT2024
On convexity and the Iwasawa decomposition of split real and complex Kac-Moody groups
Paul Zellhofer, Ralf Köhl
We prove an analogue of Kostant's convexity theorem for split real and complex Kac-Moody groups associated to free and cofree root data. The result can be seen as a first step towa…
math.GR2015
Spin covers of maximal compact subgroups of Kac-Moody groups and spin-extended Weyl groups
David Ghatei, Max Horn, Ralf Köhl +1
Let G be a split real Kac-Moody group of arbitrary type and let K be its maximal compact subgroup, i.e. the subgroup of elements fixed by a Cartan-Chevalley involution of G. We con…