Journal of Lie Theory
Vol. 9, No. 1, pp. 215-232 (1999)

Dipolarization in semisimple Lie algebras and homogeneous parakähler manifolds

S. Deng, Z. Hou, S. Kaneyuki, K. Nishiyama

Zixin Hou
Department of Mathematics
Nankai University
Tianjin 300071, P. R. China
houzx@sun.nankai.edu.cn

Shaoqiang Deng
Department of Mathematics
Nankai University
Tianjin 300071, P. R. China

Soji Kaneyuki
Department of Mathematics
Sophia University
Chiyoda-ku, Tokyo 102-8554, Japan
kaneyuki@mm.sophia.ac.jp

Kyo Nishiyama
Division of Mathematics
Faculty of Integrated Human Studies
Kyoto University
Sakyo, Kyoto 606-8501, Japan
kyo@math.h.kyoto-u.ac.jp


Abstract: A dipolarization in a Lie algebra ${\scriptstyle{\frak g}}$ is two polarizations ${\scriptstyle{\frak g}^\pm}$ in ${\scriptstyle{\frak g}}$ at a common linear form on ${\scriptstyle{\frak g}}$ satisfying ${\scriptstyle{\frak g}={\frak g}^++{\frak g}^-}$. We study dipolarizations in semisimple Lie algebras, especially, the relation between dipolarizations and gradations. As an application, we give a relation between semisimple homogeneous parak$\ddot a$hler manifolds and hyperbolic semisimple orbits. For ${\scriptstyle{\frak g}}$ real semisimple, we determine the characteristic elements, from which dipolarizations can be constructed.

Keywords: Semisimple Lie algebra, graded Lie algebra, parabolic subalgebra, dipolarization, parak$\ddot a$hler manifold.

Classification (MSC91): 17B20, 22E46, 53C12, 15, 30

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