标题： Coxeter 系统，左逆置集和高维立方体 显示英文标题

标题： Coxeter systems, left inversion sets, and higher dimensional cubes

摘要： 设$ (W,S)$为一个Coxeter系统。 我们研究方程$ w(\Phi_{x}) = \Phi_{y}$，其中$ w,x,y\in W$和$ \Phi_{x}$，$\Phi_{y}$表示$ x$和$ y$的左逆序集。 We then define a commutative square diagram called a Coxeter square which describes the relationship between 4 non-identity elements of the Coxeter group $ W$ and the equation $ w(\Phi_{x}) = \Phi_{y}$. Coxeter squares were first introduced by Dyer, Wang in \cite{dyer2011groupoids2} and \cite{dyer2019characterization}. Coxeter squares can be \textquotedblleft glued" together by compatible edges to form commutative diagrams in the shape of higher dimensional cubes called Coxeter $n$-cubes, which were first defined by Dyer in Example 12.5 of \cite{dyer2011groupoids2}. 当 $ |W| < \infty$ 和 $ |S| = n$时，我们证明了 Coxeter $n$-立方体必须存在于 $ (W,S)$ 中。 然后我们证明了关于 Coxeter $n$-立方体在 $A_{n}$ Coxeter 系统中的结果。 我们建立了在$ A_{n}$中 Coxeter$n$-立方体（模向）与具有$n+1$个叶子的二叉树之间的显式双射。 我们还证明，$x$是$ A_{n}$中的一个元素，当且仅当$ x$是一个双格拉斯曼排列时，它会作为某个 Coxeter$n$-立方体的边出现。 显示英文摘要

摘要： Let $ (W,S)$ be a Coxeter system. We investigate the equation $ w(\Phi_{x}) = \Phi_{y}$ where $ w,x,y\in W$ and $ \Phi_{x}$, $\Phi_{y}$ denote the left inversion sets of $ x$ and $ y$. We then define a commutative square diagram called a Coxeter square which describes the relationship between 4 non-identity elements of the Coxeter group $ W$ and the equation $ w(\Phi_{x}) = \Phi_{y}$. Coxeter squares were first introduced by Dyer, Wang in \cite{dyer2011groupoids2} and \cite{dyer2019characterization}. Coxeter squares can be \textquotedblleft glued" together by compatible edges to form commutative diagrams in the shape of higher dimensional cubes called Coxeter $n$-cubes, which were first defined by Dyer in Example 12.5 of \cite{dyer2011groupoids2}. When $ |W| < \infty$ and $ |S| = n$, we show that Coxeter $n$-cubes must exist within $ (W,S)$. We then prove results about Coxeter $n$-cubes in the $A_{n}$ Coxeter system. We establish an explicit bijection between Coxeter $n$-cubes (modulo orientation) in $ A_{n}$ and binary trees with $n+1$ leaves. We also show that an element $x$ of $ A_{n}$ appears as the edge of some Coxeter $n$-cube if and only if $ x$ is a bigrassmannian permutation.