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Andrius Kulikauskas

  • m a t h 4 w i s d o m - g m a i l
  • +370 607 27 665
  • My work is in the Public Domain for all to share freely.

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  • 读物 书 影片 维基百科

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Bott periodicity, Lie group embeddings, Lie theory

Understand Lie group embeddings in terms of Dynkin diagrams


Dynkin diagrams



Dynkin diagrams for classical Lie algebras

I want to consider how the chain of embeddings of Lie algebras can be understood in terms of their Dynkin diagrams.

Note that the Dynkin diagrams are related to the Lie algebras over {$\mathbb{C}$}. Whereas the unitary group {$\frak{u}$}(n)$} of skew-Hermitian matrices is a Lie algebra over {$\mathbb{R}$}. For {$i$} times a skew-Hermitian matrix is Hermitian.

  • {$A_n=\frak{sl}$}{$(n+1)$} The maximal compact subgroup is {$SU(n+1)$}.
  • {$C_n=\frak{sp}$}{$(2n)$} The maximal compact subgroup is {$Sp(2n)$}.
  • {$D_n=\frak{o}$}{$(2n)$} The maximal compact subgroup is {$SO(2n)$}.
Lie groupnodesdiagramzero
{$U(2r)$}2r - 1{$\circ - \circ - \circ - \circ$}dual
{$U(r)\times U(r)$}2r - 2{$\circ - \circ - \circ - \circ \;\;\;\; \circ - \circ - \circ - \circ$}dual
{$U(r)$}r - 1{$\circ - \circ - \circ - \circ$}dual
Lie groupnodesdiagramzero
{$O(32r)$}8r{$\circ - \circ - \circ \langle \begin{matrix}\circ \\ \circ \\ \end{matrix} $}folding
{$U(16r)$}8r - 1{$\circ - \circ - \circ - \circ$}dual
{$Sp(8r)$}4r{$\circ - \circ - \circ -- \circ$}fusing
{$Sp(4r)\times Sp(4r)$}4r{$\circ - \circ - \circ -- \circ \;\;\;\; \circ - \circ - \circ -- \circ$}fusing disconnected
{$Sp(4r)$}2r{$\circ - \circ - \circ -- \circ$}fusing
{$U(4r)$}4r-1{$\circ - \circ - \circ - \circ$}dual
{$O(4r)$}2r{$\circ - \circ - \circ \langle \begin{matrix}\circ \\ \circ \\ \end{matrix} $}folding
{$O(2r)\times O(2r)$}2r{$\circ - \circ - \circ \langle \begin{matrix}\circ \\ \circ \\ \end{matrix} $}folding disconnected
{$O(2r)$}r{$\circ - \circ - \circ \langle \begin{matrix}\circ \\ \circ \\ \end{matrix} $}folding
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This page was last changed on May 02, 2025, at 08:57 PM