We obtain the classification of two-orbit varieties, i.e. the normal complete complex algebraic varieties on which a reductive complex algebraic group acts with two orbits. We prove also Luna's conjecture saying that these varieties are spherical, i.e. admit a dense orbit of a Borel subgroup.
Cite this article
Stéphanie Cupit-Foutou, Classification of two-orbit varieties. Comment. Math. Helv. 78 (2003), no. 2, pp. 245–265DOI 10.1007/S000140300011