Orbits of strongly solvable spherical subgroups on the flag variety

Let G be a connected reductive complex algebraic group and B a Borel subgroup of G. We consider a subgroup H ⊂ B which acts with finitely many orbits on the flag variety G/B, and we classify the H-orbits in G/B in terms of suitable root systems. As well, we study the Weyl group action defined by Knop on the set of H -orbits in G/B, and we give a combinatorial model for this action in terms of weight polytopes.

Let G be a connected reductive complex algebraic group and B a Borel subgroup of G. We consider a subgroup H⊂ B which acts with finitely many orbits on the flag variety G / B, and we classify the H-orbits in G / B in terms of suitable root systems. As well, we study the Weyl group action defined by Knop on the set of H-orbits in G / B, and we give a combinatorial model for this action in terms of weight polytopes.