Abstract
Let G be a connected, simply connected semisimple algebraic group over the complex number field, and let K be the fixed point subgroup of an involutive automorphism of G so that (G, K) is a symmetric pair. We take parabolic subgroups P of G and Q of K, respectively, and consider the product of partial flag varieties G/P and K/Q with diagonal K-action, which we call a double flag variety for a symmetric pair. It is said to be of finite type if there are only finitely many K-orbits on it. In this paper, we give a parametrization of K-orbits on G/P × K/Q in terms of quotient spaces of unipotent groups without assuming the finiteness of orbits. If one of P ⊂ G or Q ⊂ K is a Borel subgroup, the finiteness of orbits is closely related to spherical actions. In such cases, we give a complete classification of double flag varieties of finite type, namely, we obtain classifications of K-spherical flag varieties G/P and G-spherical homogeneous spaces G/Q.
Similar content being viewed by others
References
M. Brion, A. G. Helminck, On orbit closures of symmetric subgroups in flag varieties, Canad. J. Math. 52 (2000), no. 2, 265–292.
C. Benson, G. Ratcliff, A classification of multiplicity free actions, J. Algebra 181 (1996), no. 1, 152–186.
Michel Brion, Quelques propriétés des espaces homogènes sphériques, Manuscripta Math. 55 (1986), no. 2, 191–198.
R. W. Carter, Finite Groups of Lie Type. Conjugacy Classes and Complex Characters, Wiley, New York, 1985.
M. Finkelberg, V. Ginzburg, On mirabolic D-modules, Int. Math. Res. Not. IMRN (2010), no. 15, 2947–2986.
M. Finkelberg, V. Ginzburg, R. Travkin, Mirabolic affine Grassmannian and character sheaves, Selecta Math. (N.S.) 14 (2009), no. 3-4, 607–628.
A. Henderson, P. E. Trapa, The exotic Robinson-Schensted correspondence, J. Algebra 370 (2012), 32–45.
A. G. Helminck, S. P. Wang, On rationality properties of involutions of reductive groups, Adv. Math. 99 (1993), no. 1, 26–96.
V. G. Kac, Some remarks on nilpotent orbits, J. Algebra 64 (1980), no. 1, 190–213.
S. Kato, An exotic Deligne–Langlands correspondence for symplectic groups, Duke Math. J. 148 (2009), no. 2, 305–371.
A. W. Knapp, Lie Groups Beyond an Introduction, 2nd ed., Progress in Mathematics, Vol. 140, Birkhäuser Boston, Boston, MA, 2002.
K. Kondo, K. Nishiyama, H. Ochiai, K. Taniguchi, Closed orbits on partial flag varieties and double flag variety of finite type, Kyushu J. Math. 68 (2014), no. 1.
A. S. Leahy, A classification of multiplicity free representations, J. Lie Theory 8 (1998), no. 2, 367–391.
P. Littelmann, On spherical double cones, J. Algebra 166 (1994), no. 1, 142–157.
G. Lusztig, Character sheaves. I–V, Adv. in Math., 56 (1985), 193–237; 57 (1985), 226–265; 57 (1985), 266–315; 59 (1986), 1–63; 61 (1986), 103–155.
G. Lusztig, D. A. Vogan, Jr., Singularities of closures of K-orbits on flag manifolds, Invent. Math. 71 (1983), no. 2, 365–379.
P. Magyar, J. Weyman, A. Zelevinsky, Multiple flag varieties of finite type, Adv. Math. 141 (1999), no. 1, 97–118.
P. Magyar, J. Weyman, A. Zelevinsky, Symplectic multiple flag varieties of finite type, J. Algebra 230 (2000), no. 1, 245–265.
K. Nishiyama, H. Ochiai, Double flag varieties for a symmetric pair and finiteness of orbits, J. Lie Theory 21 (2011), no. 1, 79–99.
D. I. Panyushev, Complexity and rank of double cones and tensor product decompositions, Comment. Math. Helv. 68 (1993), no. 3, 455–468.
D. I. Panyushev, On the conormal bundle of a G-stable subvariety, Manuscripta Math. 99 (1999), no. 2, 185–202.
A. Petukhov, A geometric approach to (g, k)-modules of finite type, arXiv: 1105.5020 (2011).
R. W. Richardson, T. A. Springer, The Bruhat order on symmetric varieties, Geom. Dedicata 35 (1990), no. 1–3, 389–436.
R. W. Richardson, T. A. Springer, Combinatorics and geometry of K-orbits on the flag manifold, in: Linear Algebraic Groups and their Representations (Los Angeles, CA, 1992), Contemp. Math., Vol. 153, Amer. Math. Soc., Providence, RI, 1993, pp. 109–142.
R. W. Richardson, T. A. Springer, Complements to: “The Bruhat order on symmetric varieties” [Geom. Dedicata 35(1990), no. 1–3, 389–436], Geom. Dedicata 49 (1994), no. 2, 231–238.
T. A. Springer, Algebraic groups with involutions, in: Proceedings of the 1984 Vancouver Conference in Algebraic Geometry CMS Conf. Proc., Vol. 6, American Mathematical Society, Providence, RI , 1986, pp. 461–471.
T. A. Springer, Linear Algebraic Groups, 2nd ed., Progress in Mathematics, Vol. 9, Birkhäuser Boston, Boston, MA, 1998.
R. Steinberg, Endomorphisms of Linear Algebraic Groups, Memoirs of the American Mathematical Society, no. 80, American Mathematical Society, Providence, RI, 1968.
J. R. Stembridge, Multiplicity-free products and restrictions of Weyl characters, Represent. Theory 7 (2003), 404–439 (electronic).
Y. Tanaka, Classification of visible actions on flag varieties, Proc. Japan Acad. Ser. A Math. Sci. 88 (2012), no. 6, 91–96.
R. Travkin, Mirabolic Robinson–Schensted–Knuth correspondence, Selecta Math. (N.S.) 14 (2009), no. 3–4, 727–758.
Э. Б. Винберг, Cлoжнoсмь дeйсmвuй рeдyкmuвных групп, фyнкц. анализ и его прилож 20 (1986), no. 1, 1–13. Engl. transl.: È. B. Vinberg, Complexity of action of reductive groups, Funct. Anal. Appl. 20 (1986), no. 1, 1–11.
Э. Б. Винберг, Б. H. Кимельфельд, Однородные обласmu на флаговых многообразuях u cферческuе nодгруnnы nолуnроmых групп Лu, функц. анализ и его прилоҗ. 12 (1978), no. 3, 12–19. Engl. transl.: È. B. Vinberg, B. N. Kimel’fel’d, Homogeneous domains on flag manifolds and spherical subgroups of semisimple Lie groups, Funct. Anal. Appl. 12 (1979), no. 3, 168–174.
T. Vust, Opération de groupes réductifs dans un type de cônes presque homogènes, Bull. Soc. Math. France 102 (1974), 317–333.
Author information
Authors and Affiliations
Corresponding author
Additional information
(XUHUA HE) Partially supported by HKRGC grant 602011
(KYO NISHIYAMA) Supported by JSPS Grant-in-Aid for Scientific Research (B) #21340006
(HIROYUKI OCHIAI) Supported by JSPS Grant-in-Aid for Scientific Research (A) #19204011, and JST CREST.
(YOSHIKI OSHIMA) Supported by Grant-in-Aid for JSPS Fellows (10J00710).
Dedicated to Jiro Sekiguchi on the occasion of his sixtieth birthday
Rights and permissions
About this article
Cite this article
HE, X., OCHIAI, H., NISHIYAMA, K. et al. On Orbits in Double Flag Varieties for Symmetric Pairs. Transformation Groups 18, 1091–1136 (2013). https://doi.org/10.1007/s00031-013-9243-8
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00031-013-9243-8