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arXiv 1402.0211math.CO
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符号弧置换

Signed arc permutations

Sergi Elizalde, Yuval Roichman

摘要:

弧排列最初是在三角剖分和特征标的研究中引入的,最近被证明具有有趣的组合性质。本文的第一部分继续他们的研究,提供了关于他们的下降集和主要指标的符号计数公式。接下来,我们将弧置换的概念从两个不同的方向推广到超八面体群。我们发现,这些扩展类型$B$进行有趣的类似物的性质类型$A$弧排列,如特征的模式避免,优雅的无符号和有符号枚举公式的标志主要指标。

英文摘要:

Arc permutations, which were originally introduced in the study of triangulations and characters, have recently been shown to have interesting combinatorial properties. The first part of this paper continues their study by providing signed enumeration formulas with respect to their descent set and major index. Next, we generalize the notion of arc permutations to the hyperoctahedral group in two different directions. We show that these extensions to type $B$ carry interesting analogues of the properties of type $A$ arc permutations, such as characterizations by pattern avoidance, and elegant unsigned and signed enumeration formulas with respect to the flag-major index.

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