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arXiv 1907.12964math.RTmath.SG
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约化李群不可约表示的容许限制:辛几何与离散可分解性

Admissible restrictions of irreducible representations of reductive Lie groups: symplectic geometry and discrete decomposability

Toshiyuki Kobayashi

AI总结:

本文利用辛几何方法刻画实约化李群不可约容许表示中紧子群 L-型重数有限的充要条件,并据此简化酉表示限制离散可分解性判据的证明、补足其逆命题。

摘要:

设 $G$ 为实约化李群,$L$ 为紧子群,$\pi$ 为 $G$ 的不可约容许表示。本文中,我们运用辛方法证明了 $\pi$ 中出现的 $L$-型重数有限的充要条件。这使我们能够对酉表示关于非紧子群限制的离散可分解性判据(作者,《Ann. Math.》,1998年)给出一个简洁证明,同时也证明了曾在 [Proc. ICM 2002, Thm.D] 中宣布的逆命题。文中还给出了若干与 Kostant 凸性定理以及非黎曼局部对称空间相关的例子。

英文摘要:

Let $G$ be a real reductive Lie group, $L$ a compact subgroup, and $π$ an irreducible admissible representation of $G$. In this article we prove a necessary and sufficient condition for the finiteness of the multiplicities of $L$-types occurring in $π$ based on symplectic techniques. This leads us to a simple proof of the criterion for discrete decomposability of the restriction of unitary representations with respect to noncompact subgroups (the author, Ann. Math. 1998), and also provides a proof of a reverse statement which was announced in [Proc.ICM 2002, Thm.D]. A number of examples are presented in connection with Kostant's convexity theorem and also with non-Riemannian locally symmetric spaces.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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