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阿波罗圆填充:几何与群论III。更高维度

Apollonian Circle Packings: Geometry and Group Theory III. Higher Dimensions

R. L. Graham, J. C. Lagarias, C. L. Mallows, A. R. Wilks, C. H. Yan

摘要:

本文在第一部分和第二部分中给出了Apollonian圆填充的$n$ -维类似物.我们工作在空间$\sM_{\dd}^n$的所有$n$维定向笛卡尔配置参数化的坐标系,ACC坐标,作为那些$(n+2) \times (n+2)$实矩阵$\bW$与$\bW^T \bQ_{D,n} \bW = \bQ_{W,n}$其中$Q_{D,n} = x_1^2 +... + x_{n+2}^2 - \frac{1}{n}(x_1 +... + x_{n+2})^2$是$n$维笛卡尔二次型,$Q_{W,n} = -8x_1x_2 + 2x_3^2 + ... + 2x_{n+2}^2$,和$\bQ_{D,n}$和$\bQ_{W,n}$是它们相应的对称矩阵。在参数空间$\sM_{\dd}^n$上有自然的动作。我们介绍$n$维类似物的阿波罗群,对偶阿波罗群和超阿波罗群。这些是具有以下积分性质的双生成群:对偶阿波罗群由所有维度的积分矩阵组成,而其他两个由有理矩阵组成,其中的分解子具有从有限集合$S$中提取的素因子,这取决于维度。我们证明了Apollonian群和对偶Apollonian群的存在性,并且证明了它们是Coxeter群.我们定义一个阿波罗集群合奏下的阿波罗组的任何轨道,与其他两个群体类似的概念。我们确定在哪些维度可以找到合理的阿波罗集群合奏(所有曲率合理)和强合理的阿波罗球合奏(所有ACC坐标合理)。

英文摘要:

This paper gives $n$-dimensional analogues of the Apollonian circle packings in parts I and II. We work in the space $\sM_{\dd}^n$ of all $n$-dimensional oriented Descartes configurations parametrized in a coordinate system, ACC-coordinates, as those $(n+2) \times (n+2)$ real matrices $\bW$ with $\bW^T \bQ_{D,n} \bW = \bQ_{W,n}$ where $Q_{D,n} = x_1^2 +... + x_{n+2}^2 - \frac{1}{n}(x_1 +... + x_{n+2})^2$ is the $n$-dimensional Descartes quadratic form, $Q_{W,n} = -8x_1x_2 + 2x_3^2 + ... + 2x_{n+2}^2$, and $\bQ_{D,n}$ and $\bQ_{W,n}$ are their corresponding symmetric matrices. There are natural actions on the parameter space $\sM_{\dd}^n$. We introduce $n$-dimensional analogues of the Apollonian group, the dual Apollonian group and the super-Apollonian group. These are finitely generated groups with the following integrality properties: the dual Apollonian group consists of integral matrices in all dimensions, while the other two consist of rational matrices, with denominators having prime divisors drawn from a finite set $S$ depending on the dimension. We show that the the Apollonian group and the dual Apollonian group are finitely presented, and are Coxeter groups. We define an Apollonian cluster ensemble to be any orbit under the Apollonian group, with similar notions for the other two groups. We determine in which dimensions one can find rational Apollonian cluster ensembles (all curvatures rational) and strongly rational Apollonian sphere ensembles (all ACC-coordinates rational).

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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