Degenerations of spherical subalgebras and spherical roots

Abstract

We obtain several structure results for a class of spherical subgroups of connected reductive complex algebraic groups that extends the class of strongly solvable spherical subgroups. Based on these results, we construct certain one-parameter degenerations of the Lie algebras corresponding to such subgroups. As an application, we exhibit explicit algorithms for computing the set of spherical roots of such a spherical subgroup.Comment: v2: 45 pages, revised extended version with new Section 6 containing an optimization of the initial algorith