arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0904.2194math.CO
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根多面体,三角剖分,和细分代数,我

Root polytopes, triangulations, and the subdivision algebra, I

Karola Meszaros

摘要:

A_n型全根多面体是R^{n+1}中原点和点e_i-e_j(1<= i<j <= n+1)的凸包。给定顶点集[n+1]上的树T,其根多面体P(T)是全根多面体与向量e_i-e_j生成的锥的交,其中(i,j)是T的一条边,i<j.在约化x_{ij} x_{ij}--> x_{ik} x_{ij} + x_{jk} x_{ik} +β x_{ik}下,给出了交换变量x_{ij}中某个单项式m[T]的约化形式,可以解释为P(T)的三角剖分。利用这些三角剖分,得到了P(T)的体积和Ehrhart多项式。如果我们允许变量x_{ij}和x_{kl}仅在i,j,k,l不同时交换,则m[T]的简化形式是唯一的,并产生P(T)的规范三角剖分,其中每个单形对应于一个不相交的交错森林。最一般地说,在非对易情形下,所有单项式的约化形式都是唯一的。

英文摘要:

The type A_n full root polytope is the convex hull in R^{n+1} of the origin and the points e_i-e_j for 1<= i<j <= n+1. Given a tree T on the vertex set [n+1], the associated root polytope P(T) is the intersection of the full root polytope with the cone generated by the vectors e_i-e_j, where (i, j) is an edge of T, i<j. The reduced forms of a certain monomial m[T] in commuting variables x_{ij} under the reduction x_{ij}x_{jk} --> x_{ik}x_{ij}+x_{jk}x_{ik}+βx_{ik}, can be interpreted as triangulations of P(T). Using these triangulations, the volume and Ehrhart polynomial of P(T) are obtained. If we allow variables x_{ij} and x_{kl} to commute only when i, j, k, l are distinct, then the reduced form of m[T] is unique and yields a canonical triangulation of P(T) in which each simplex corresponds to a noncrossing alternating forest. Most generally, the reduced forms of all monomials in the noncommutative case are unique.

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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