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We generalize proper coloring of gain graphs to totally frustrated states, where each vertex takes a value in a set of `qualities' or `spins' that is permuted by the gain group. (An example is the Potts model.) The number of totally…

Combinatorics · Mathematics 2010-01-24 Thomas Zaslavsky

The generalized composition graph is used by Cardoso and some researchers for factorization of the adjacency spectrum and Laplacian of a simple graph. Because the generalized composition graph is an example of a set-theoretic linear operad,…

Combinatorics · Mathematics 2026-05-01 Jean Liendo

Given a graph G, a colouring is an assignment of colours to the vertices of G so that no two adjacent vertices are coloured the same. If all colour classes have size at most t, then we call the colouring t-bounded, and the t-bounded…

Combinatorics · Mathematics 2024-09-27 Annika Heckel , Konstantinos Panagiotou

Gessel and Sagan investigated the Tutte polynomial, $T(x,y)$ using depth first search, and applied their techniques to show that the number of acyclic partial orientations of a graph is $2^gT(3,1/2)$. We provide a short deletion-contraction…

Combinatorics · Mathematics 2015-03-20 Spencer Backman

We study the Tutte polynomial of two infinite families of finite graphs. These are the Schreier graphs associated with the action of two well-known self-similar groups acting on the binary rooted tree by automorphisms: the first Grigorchuk…

Combinatorics · Mathematics 2016-02-16 Tullio Ceccherini-Silberstein , Alfredo Donno , Donatella Iacono

Let $G = (V, E)$ be a simple graph of order $n$. The total dominating set of $G$ is a subset $D$ of $V$ that every vertex of $V$ is adjacent to some vertices of $D$. The total domination number of $G$ is equal to minimum cardinality of…

Combinatorics · Mathematics 2017-05-03 Saeid Alikhani , Nasrin Jafari

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…

Combinatorics · Mathematics 2024-06-25 Graham Farr , Kerri Morgan

We address the enumeration of q-coloured planar maps counted bythe number of edges and the number of monochromatic edges. We prove that the associated generating function is differentially algebraic,that is, satisfies a non-trivial…

Combinatorics · Mathematics 2025-04-11 Olivier Bernardi , Mireille Bousquet-Mélou

Some important properties of the chromatic polynomial also hold for any polynomial set map satisfying p_S(x+y)=\sum_{T\uplus U=S}p_T(x)p_U(y). Using umbral calculus, we give a formula for the expansion of such a set map in terms of any…

Combinatorics · Mathematics 2007-07-06 Gus Wiseman

Let $\Gamma$ be an Abelian group and let $G$ be a simple graph. We say that $G$ is $\Gamma$-colorable if for some fixed orientation of $G$ and every edge labeling $\ell:E(G)\rightarrow \Gamma$, there exists a vertex coloring $c$ by the…

Combinatorics · Mathematics 2023-12-05 Bartłomiej Bosek , Jarosław Grytczuk , Grzegorz Gutowski , Oriol Serra , Mariusz Zając

This work is divided into three parts. The first part concerns polynomials in one variable with all real roots. We consider linear transformations that preserve real rootedness, as well as matrices that preserve interlacing. The second part…

Classical Analysis and ODEs · Mathematics 2008-03-11 Steve Fisk

This paper serves as the first extension of the topic of dominator colorings of graphs to the setting of digraphs. We establish the dominator chromatic number over all possible orientations of paths and cycles. In this endeavor we discover…

Combinatorics · Mathematics 2019-02-21 Michael Cary

We bound the location of roots of polynomials that have nonnegative coefficients with respect to a fixed but arbitrary basis of the vector space of polynomials of degree at most $d$. For this, we interpret the basis polynomials as vector…

Combinatorics · Mathematics 2009-11-16 Julian Pfeifle

The independence polynomial of a graph is the generating polynomial for the number of independent sets of each cardinality and its roots are called independence roots. We investigate here purely imaginary independence roots. We show that…

Combinatorics · Mathematics 2020-03-31 Ben Cameron , Jason I. Brown

The deletion--contraction algorithm is perhaps the most popular method for computing a host of fundamental graph invariants such as the chromatic, flow, and reliability polynomials in graph theory, the Jones polynomial of an alternating…

Data Structures and Algorithms · Computer Science 2008-04-14 Andreas Björklund , Thore Husfeldt , Petteri Kaski , Mikko Koivisto

Tutte has described in the book "Connectivity in graphs" a canonical decomposition of any graph into 3-connected components. In this article we translate (using the language of symbolic combinatorics) Tutte's decomposition into a general…

Combinatorics · Mathematics 2012-04-19 Guillaume Chapuy , Eric Fusy , Mihyun Kang , Bilyana Shoilekova

We study a relation between roots of characteristic polynomials and intersection points of line arrangements. Using these results, we obtain a lot of applications for line arrangements. Namely, we give (i) a generalized addition theorem for…

Combinatorics · Mathematics 2014-04-17 Takuro Abe

Let $G$ be a simple graph. A total dominator coloring of $G$ is a proper coloring of the vertices of $G$ in which each vertex of the graph is adjacent to every vertex of some color class. The total dominator chromatic number $\chi_d^t(G)$…

Combinatorics · Mathematics 2015-11-06 Saeid Alikhani , Nima Ghanbari

The smallest integer $k$ needed for the assignment of colors to the elements so that the coloring is proper (vertices and edges) is called the total chromatic number of a graph. Vizing and Behzed conjectured that the total coloring can be…

Combinatorics · Mathematics 2018-12-17 Geetha Jayabalan , Narayanan N , K Somasundaram

Specializing the $\gamma$-basis for the vector space $\mathcal{G}(n,r)$ spanned by the set of symbols on bit sequences with $r$ $1$'s and $n-r$ $0$'s, we obtain a frame or spanning set for the vector space $\mathcal{T}(n,r)$ spanned by…

Combinatorics · Mathematics 2021-06-08 Joseph P. S. Kung
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