Grassmannian perspectives of classical Lie groups and Cartan involutions

Fuente: arXiv
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Autori principali: Chen, Yunxia, Leung, Naichung Conan
Natura: Preprint
Pubblicazione: 2026
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author Chen, Yunxia
Leung, Naichung Conan
author_facet Chen, Yunxia
Leung, Naichung Conan
contents Classical noncompact reductive Lie group $G$ admits a compactification $\overline{G}$ as a Riemannian symmetric space by He. First, we provide a unified construction of these compactifications via Grassmannian geometry and realize the group structures in terms of the geometry of configurations of linear subspaces. Second, we show that the Cartan involution $ρ$ on $G$ extends uniquely to an isometric involution $\barρ$ on $\overline{G}$ and $\overline{G}^{\barρ} = G^ρ = K$, the maximal compact subgroup of $G$. Third, we show that $η(g) = ρ(g)^{-1}$ extends uniquely to an isometric involution $\barη$ on $\overline{G}$ and $\overline{G}^{\barη} = G_c/K$, the compact symmetric space dual to $(G^η)_0 = G/K$. This provides a natural generalization of the classical Borel embeddings $G/K \hookrightarrow G_c/K$. Furthermore, $K$ and $G_c/K$ form a complementary pair of reflective submanifolds in $\overline{G}$.
format Preprint
id arxiv_https___arxiv_org_abs_2602_00602
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Grassmannian perspectives of classical Lie groups and Cartan involutions
Chen, Yunxia
Leung, Naichung Conan
Differential Geometry
Classical noncompact reductive Lie group $G$ admits a compactification $\overline{G}$ as a Riemannian symmetric space by He. First, we provide a unified construction of these compactifications via Grassmannian geometry and realize the group structures in terms of the geometry of configurations of linear subspaces. Second, we show that the Cartan involution $ρ$ on $G$ extends uniquely to an isometric involution $\barρ$ on $\overline{G}$ and $\overline{G}^{\barρ} = G^ρ = K$, the maximal compact subgroup of $G$. Third, we show that $η(g) = ρ(g)^{-1}$ extends uniquely to an isometric involution $\barη$ on $\overline{G}$ and $\overline{G}^{\barη} = G_c/K$, the compact symmetric space dual to $(G^η)_0 = G/K$. This provides a natural generalization of the classical Borel embeddings $G/K \hookrightarrow G_c/K$. Furthermore, $K$ and $G_c/K$ form a complementary pair of reflective submanifolds in $\overline{G}$.
title Grassmannian perspectives of classical Lie groups and Cartan involutions
topic Differential Geometry
url https://arxiv.org/abs/2602.00602