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hyperoctahedral_group [2020/02/13 06:33]
amang [Hyperoctahedral group]
hyperoctahedral_group [2021/11/23 11:56] (current)
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 ====== Hyperoctahedral group ====== ====== Hyperoctahedral group ======
  
-A **hyperoctahedral group** is any member of a sequence $(H_N)_{N\in \N}$ of [[classical ​matrix group|classical ​matrix groups]].+A **hyperoctahedral group** is any member of a sequence $(H_N)_{N\in \N}$ of [[classical ​orthogonal ​matrix groups]].
  
 ===== Definition ===== ===== Definition =====
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 For every $N\in \N$ the hyperoctahedral group $H_N$ for dimension $N$ can be defined as the subgroup of the [[wp>​general linear group]] $\mathrm{GL}(N,​\C)$ given by all orthogonal $N\times N$-matrices with integer entries, i.e., the set For every $N\in \N$ the hyperoctahedral group $H_N$ for dimension $N$ can be defined as the subgroup of the [[wp>​general linear group]] $\mathrm{GL}(N,​\C)$ given by all orthogonal $N\times N$-matrices with integer entries, i.e., the set
 $$H_N\colon\hspace{-0.6em}=\{ u\in \C^{N\times N}\,\vert\, u=\overline{u},​\,​ uu^t=u^tu=I,​ \,​\forall_{i,​j=1}^N: ​ u_{i,​j}\in\Z\},​$$ $$H_N\colon\hspace{-0.6em}=\{ u\in \C^{N\times N}\,\vert\, u=\overline{u},​\,​ uu^t=u^tu=I,​ \,​\forall_{i,​j=1}^N: ​ u_{i,​j}\in\Z\},​$$
-where, if $u=(u_{i,​j})_{i,​j=1}^N$,​ then $\overline u=(u^\ast_{i,​j})_{i,​j=1}^N$ is the complex conjugate of $u$ and $u^t=(u_{j,​i})_{i,​j=1}^N$ the transpose and where $I_N$ is the identity $N\!\times \!N$-matrix.+where, if $u=(u_{i,​j})_{i,​j=1}^N$,​ then $\overline u=(\overline{u}_{i,​j})_{i,​j=1}^N$ is the complex conjugate of $u$ and $u^t=(u_{j,​i})_{i,​j=1}^N$ the transpose and where $I_N$ is the identity $N\!\times \!N$-matrix.
  
  
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 For the hyperoctahedral group $H_N$ this  means that $H_N=\Z_2\wr S_N$ is given by the group with underlying set $(\Z_2)^{\times N}\times S_N$ and group law $(((i_1,​\ldots,​i_N),​\pi),​((j_1,​\ldots,​j_N),​\rho))\mapsto ((i_1+j_{\pi^{-1}(1)},​\ldots,​i_N+j_{\pi^{-1}(N)}),​\pi\circ \rho)$. For the hyperoctahedral group $H_N$ this  means that $H_N=\Z_2\wr S_N$ is given by the group with underlying set $(\Z_2)^{\times N}\times S_N$ and group law $(((i_1,​\ldots,​i_N),​\pi),​((j_1,​\ldots,​j_N),​\rho))\mapsto ((i_1+j_{\pi^{-1}(1)},​\ldots,​i_N+j_{\pi^{-1}(N)}),​\pi\circ \rho)$.
  
 +
 +===== Basic properties =====
 +
 +The hyperoctahedral groups $(B_N)_{N\in \N}$ are an [[easy_quantum_group|easy]] family of compact matrix quantum groups, i.e., the intertwiner spaces of their corepresentation categories are induced by a [[category of partitions]]. More precisely, it is the [[category of partitions with blocks of even size]] that induces the corepresentation categories of $(H_N)_{N\in \N}$. Its canonical generating set of partitions is $\{\crosspart,​\fourpart\}$. ​
 +
 +===== Representation theory =====
 +
 +===== Cohomology =====
 +
 +===== Related quantum groups =====
 +
 +===== References =====
hyperoctahedral_group.1581575627.txt.gz · Last modified: 2021/11/23 11:56 (external edit)