A uniform description of compact symmetric spaces as Grassmannians using the magic square

作者:Huang Yongdong; Leung Naichung Conan*
来源:Mathematische Annalen, 2011, 350(1): 79-106.
DOI:10.1007/s00208-010-0549-8

摘要

Suppose A and B are normed algebras, i.e. R, C, H or O, E, we introduce and study Grassmannians of linear subspaces in ( A circle times B)n which are complex/Lagrangian/maximal isotropic with respect to natural two tensors on ( A circle times B)n . We show that every irreducible compact symmetric space must be one of these Grassmannian spaces, possibly up to a finite cover. This gives a simple and uniform description of all compact symmetric spaces. This generalizes the Tits magic square description for simple Lie algebras to compact symmetric spaces.

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