Left cells in the weighted Coxeter group ${\bm {\widetilde C}_{\bm n}}$
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摘要: 仿射~Weyl~群~($\widetilde{A}_{2n},\widetilde{S}$) 在某个群同构~$\alpha$~(其中~$\alpha(\widetilde{S}) = \widetilde{S}$)~下的固定点集合 能被看作是仿射~Weyl~群~($\widetilde{C}_n,S$). 那么加权的~Coxeter~群\ ($\widetilde{C}_n,\widetilde{\ell}$)的左和双边胞腔($\widetilde{\ell}$ 是仿射~Weyl~群~$\widetilde{A}_{2n}$~的长度函数), 就能通过研究仿射~Weyl~群~($\widetilde{A}_{2n},\widetilde{S}$) 在群同构~$\alpha$~下的固定点集合而给出一个清晰的划分. 因此给出了加权的~Coxeter~群~($\widetilde{C}_n,\widetilde{\ell}$) 对应于划分\ $\textbf{k}\textbf{1}^{\textbf{2n+1-k}}$~和~$(2n-1,2)$ 的所有左胞腔的清晰刻画, 这里对所有的~$1\leqslant k \leqslant 2n+1$.
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关键词:
- 仿射~Weyl~群 /
- 左胞腔 /
- 拟分裂 /
- 加权的~Coxeter~群
Abstract: The fixed point set of the affine Weyl group ($\widetilde{A}_{2n},\widetilde{S}$) under a certain group automorphism $\alpha$ with $\alpha\,(\widetilde{S}) = \widetilde{S}$ can be considered as the affine Weyl group ($\widetilde{C}_n,S$). Then the left and two-sided cells of the weighted Coxeter group ($\widetilde{C}_n,\widetilde{\ell}$), where $\widetilde{\ell}$ is the length function of $\widetilde{A}_{2n}$, can be given an explicit description by studying the fixed point set of the affine Weyl group ($\widetilde{A}_{2n},\widetilde{S}$) under $\alpha$. We describe the cells of ($\widetilde{C}_n,\widetilde{\ell}$) corresponding to the partitions $\textbf{k}\textbf{1}^{\textbf{2n+1-k}}$ with $1\leqslant k \leqslant 2n+1$ and $(2n-1,2)$.-
Key words:
- affine Weyl groups /
- left cells /
- quasi-split case /
- weighted Coxeter group
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