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In "A survey on the Turaev genus of knots," Champanerkar and Kofman propose several open questions. The first asks whether the polynomial whose coefficients count the number of quasi-trees of the all-A ribbon graph obtained from a diagram…

几何拓扑 · 数学 2016-02-23 Cody Armond , Moshe Cohen

It is well known that the coefficients of the matching polynomial are unimodal. Unimodality of the coefficients (or their absolute values) of other graph polynomials have been studied as well. One way to prove unimodality is to prove…

组合数学 · 数学 2022-10-19 Johann A. Makowsky , Vsevolod Rakita

Given a graph $G$, its genus polynomial is $\Gamma_G(x) = \sum_{k\geq 0} g_k(G)x^k$, where $g_k(G)$ is the number of 2-cell embeddings of $G$ in an orientable surface of genus $k$. The Log-Concavity Genus Distribution (LCGD) Conjecture…

组合数学 · 数学 2022-12-21 MacKenzie Carr , Varpreet Dhaliwal , Bojan Mohar

We provide recipe theorems for the Bollob\`as and Riordan polynomial $\mathcal{R}$ defined on classes of ribbon graphs with half-edges introduced in arXiv:1310.3708[math.GT]. We also define a generalized transition polynomial $Q$ on this…

组合数学 · 数学 2014-10-28 Remi C. Avohou , Joseph Ben Geloun , Mahouton N. Hounkonnou

For an arbitrary partially ordered set $P$ its {\em dual} $P^*$ is built as the collection of all monotone mappings $P\to\2$ where $\2=\{0,1\}$ with $0<1$. The set of mappings $P^*$ is proved to be a complete lattice with respect to the…

范畴论 · 数学 2007-05-23 Roman R. Zapatrin

We study the neighborhood polynomial and the complexity of its computation for chordal graphs. The neighborhood polynomial of a graph is the generating function of subsets of its vertices that have a common neighbor. We introduce a…

组合数学 · 数学 2023-06-22 Helena Bergold , Winfried Hochstättler , Uwe Mayer

In this paper we consider the separability problem for bipartite quantum states arising from graphs. Earlier it was proved that the degree criterion is the graph-theoretic counterpart of the familiar positive partial transpose criterion for…

量子物理 · 物理学 2016-07-29 Supriyo Dutta , Bibhas Adhikari , Subhashish Banerjee , R. Srikanth

Graph-based semantic representations are valuable in natural language processing, where it is often simple and effective to represent linguistic concepts as nodes, and relations as edges between them. Several attempts has been made to find…

形式语言与自动机理论 · 计算机科学 2021-05-10 Johanna Björklund , Frank Drewes , Anna Jonsson

Mutual-visibility sets were motivated by visibility in distributed systems and social networks, and intertwine with several classical mathematical areas. Monotone properties of the variety of mutual-visibility sets, and restrictions of such…

组合数学 · 数学 2025-12-10 Csilla Bujtás , Sandi Klavžar , Jing Tian

In 2009 Chmutov introduced the idea of partial duality for embeddings of graphs in surfaces. We discuss some alternative descriptions of partial duality, which demonstrate the symmetry between vertices and faces. One is in terms of band…

组合数学 · 数学 2016-05-02 M. N. Ellingham , Xiaoya Zha

We extend to infinite graphs the matroidal characterization of finite graph duality, that two graphs are dual iff they have complementary spanning trees in some common edge set. The naive infinite analogue of this fails. The key in an…

组合数学 · 数学 2011-06-08 Reinhard Diestel , Julian Pott

Let $\mathcal S$ be a set of monic degree $2$ polynomials over a finite field and let $C$ be the compositional semigroup generated by $\mathcal S$. In this paper we establish a necessary and sufficient condition for $C$ to be consisting…

数论 · 数学 2019-02-13 Andrea Ferraguti , Giacomo Micheli , Reto Schnyder

The matching polynomial of a graph is the generating function of the numbers of its matchings with respect to their cardinality. A graph polynomial is polynomial reconstructible, if its value for a graph can be determined from its values…

组合数学 · 数学 2014-04-15 Xueliang Li , Yongtang Shi , Martin Trinks

Treewidth is a parameter that emerged from the study of minor closed classes of graphs (i.e. classes closed under vertex and edge deletion, and edge contraction). It in some sense describes the global structure of a graph. Roughly, a graph…

组合数学 · 数学 2022-02-02 Tara Abrishami , Maria Chudnovsky , Kristina Vušković

We introduce an additional structure on ribbon graphs, arrow structure. We extend the Bollob\'as-Riordan polynomial to ribbon graph with this structure. The extended polynomial satisfies the contraction-deletion relations and naturally…

组合数学 · 数学 2015-03-19 Robert Bradford , Clark Butler , Sergei Chmutov

Motivated by the definition of the edge elimination polynomial of a graph we define the covered components polynomial counting spanning subgraphs with respect to their number of components, edges and covered components. We prove a…

组合数学 · 数学 2012-03-02 Martin Trinks

We present a refinement of Ramsey numbers by considering graphs with a partial ordering on their vertices. This is a natural extension of the ordered Ramsey numbers. We formalize situations in which we can use arbitrary families of…

组合数学 · 数学 2016-11-29 Christopher Cox , Derrick Stolee

The Bollobas-Riordan polynomial [Math. Ann. 323, 81 (2002)] extends the Tutte polynomial and its contraction/deletion rule for ordinary graphs to ribbon graphs. Given a ribbon graph $\cG$, the related polynomial should be computable from…

组合数学 · 数学 2013-11-08 Remi C. Avohou , Joseph Ben Geloun , Etera R. Livine

We give a method of generating strongly polynomial sequences of graphs, i.e., sequences $(H_{\mathbf{k}})$ indexed by a multivariate parameter $\mathbf{k}=(k_1,\ldots, k_h)$ such that, for each fixed graph $G$, there is a multivariate…

组合数学 · 数学 2013-08-20 Delia Garijo , Andrew Goodall , Jaroslav Nesetril

We raise some questions about graph polynomials, highlighting concepts and phenomena that may merit consideration in the development of a general theory. Our questions are mainly of three types: When do graph polynomials have reduction…

组合数学 · 数学 2024-06-25 Graham Farr , Kerri Morgan