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Partial duality for ribbon graphs, II: Partial-twuality polynomials and monodromy computations
European Journal of Combinatorics ( IF 1.0 ) Pub Date : 2021-04-21 , DOI: 10.1016/j.ejc.2021.103329
Jonathan L. Gross , Toufik Mansour , Thomas W. Tucker

The partial (Poincaré) dual with respect to a subset A of edges of a ribbon graph G was introduced by Chmutov in connection with the Jones–Kauffman and Bollobás–Riordan polynomials. In developing the theory of maps, Wilson and others have composed Poincaré duality with Petrie duality × to give Wilson duality × and two trialities × and ×. In further expanding the theory, Abrams and Ellis-Monaghan have called the five operators twualities. Part I of this investigation (Gross et al., 2020) introduced as a partial- polynomial of G, the generating function enumerating partial Poincaré duals by Euler-genus. In this sequel, we introduce the corresponding partial-×, -×, -×, and -× polynomials for their respective twualities. For purposes of computation, we express each partial twuality in terms of the monodromy of permutations of the flags of a map. We analyze how single-edge partial twualities affect the three types (proper, untwisted, twisted) of edges. Various possible properties of partial-twuality polynomials are studied, including interpolation and log-concavity; machine-computed unimodal counterexamples to some log-concavity conjectures from Gross et al. (2020) are given. It is shown that the partial-× polynomial for a ribbon graph G equals the partial-× polynomial for G. Formulas or recursions are given for various families of graphs, including ladders and, for Wilson duality, a large subfamily of series–parallel networks. All of these polynomials are shown to be log-concave.



中文翻译:

功能区图的部分对偶,II:部分对偶多项式和单峰计算

关于子集的局部对偶(Poincaré)对偶一种 功能区图的边缘的数量 G由Chmutov结合Jones–Kauffman和Bollobás–Riordan多项式引入。在发展地图理论时,威尔逊和其他人组成了庞加莱对偶 与Petrie对偶 × 给威尔逊二元性 ×和两次审判 ××。为了进一步扩展该理论,艾布拉姆斯和埃利斯·莫纳汉(Ellis-Monaghan)称这五名操作员为二人。本次调查的第一部分(建筑等,2020)引入一个partial- 多项式的 G,该生成函数枚举Euler属的部分Poincaré对偶。在这部续集中,我们介绍了相应的partial-×,-×,-×, 和 -× 多项式的多项式。为了计算的目的,我们根据映射标志的排列的单价性来表示每个部分二重性。我们分析了单边部分成对扭曲如何影响边缘的三种类型(正确,不扭曲,扭曲)。研究了部分二元多项式的各种可能性质,包括插值和对数凹度;机器计算的单峰反例反驳了Gross等人的一些对数凹度猜想。(2020)。结果表明,部分× 功能区图的多项式 G 等于部分× 多项式 G。给出了各种图形族的公式或递归,包括梯形图,对于威尔逊对偶性,给出了一个大的系列-并行网络子族。所有这些多项式都显示为对数凹形。

更新日期:2021-04-21
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