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The structure of Cartan subgroups in Lie groups

Mathematische Zeitschrift

Abstract

We study the structure of Cartan subgroups in a connected Lie group and prove certain results which generalise the Wüstner's structure theorem for Cartan subgroups. We also show that maximal compact subgroups of the radical are contained in Cartan subgroups, and for a connected solvable Lie group, Cartan subgroups are same as those of the centralizer of maximal compact subgroups. Moreover, we describe a recipe for constructing Cartan subgroups containing certain nilpotent subgroups in a connected solvable Lie group. We prove that the image of any Cartan subgroup in the quotient group modulo a closed normal subgroup is a Cartan subgroup. Conversely, we prove that any Cartan subgroup in the quotient group is an image of a Cartan subgroup of the ambient group. We study the density of the image of any power map on a connected Lie group and show that the image of any k-th power map has dense image if its restriction to a closed normal subgroup and the corresponding map on the quotient group have dense images.