Spherical subgroups of Kac-Moody groups and transitive actions on spherical varieties
arXiv:1408.3347
Abstract
We define and study a class of spherical subgroups of a Kac-Moody group. In analogy with the standard theory of spherical varieties, we introduce a combinatorial object associated with such a subgroup, its homogeneous spherical datum, and we prove that it satisfies the same axioms as in the finite-dimensional case. Our main tool is a study of varieties that are spherical under the action of a connected reductive group L, and come equipped with a transitive action of a group containing L as a Levi subgroup.
v2: Some changes in the introduction, and added a new section with a proof of Conjecture 17.1 of version 1; v3: Final version, corrections and additional details in several proofs