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We explore the interplay between algebraic combinatorics and algorithmic problems in graph theory by defining a polynomial with connections to correspondence colouring (also known as DP-colouring), a recent generalization of list-colouring,…

Combinatorics · Mathematics 2022-12-16 Chris Godsil , Krystal Guo , Gordon Royle

A univariate graph polynomial P(G;X) is weakly distinguishing if for almost all finite graphs G there is a finite graph H with P(G;X)=P(H;X). We show that the clique polynomial and the independence polynomial are weakly distinguishing.…

Combinatorics · Mathematics 2023-06-22 Johann A. Makowsky , Vsevolod Rakita

The chromatic number $\chi(G)$ of a graph $G$ is defined as the minimum number of colours required for a vertex colouring where no two adjacent vertices are coloured the same. The chromatic number of the dense random graph $G \sim G(n,p)$…

Combinatorics · Mathematics 2021-03-29 Annika Heckel

Let G be a graph, and let $\chi$G be its chromatic polynomial. For any non-negative integers i, j, we give an interpretation for the evaluation $\chi$ (i) G (--j) in terms of acyclic orientations. This recovers the classical interpretations…

Combinatorics · Mathematics 2020-02-06 Olivier Bernardi , Philippe Nadeau

In this paper we give a new characterization of the h-vector of the chromatic polynomial of a graph. We introduce reduced chromatic cohomology of a graph and show that h_i are its Betti numbers. We then discuss various combinatorial…

Combinatorics · Mathematics 2007-05-23 Michael Chmutov , Elena Udovina

In this survey of graph polynomials, we emphasize the Tutte polynomial and a selection of closely related graph polynomials. We explore some of the Tutte polynomial's many properties and applications and we use the Tutte polynomial to…

Combinatorics · Mathematics 2008-06-28 Joanna Ellis-Monaghan , Criel Merino

A \emph{mixed graph} is a graph with directed edges, called arcs, and undirected edges. A $k$-coloring of the vertices is proper if colors from ${1,2,...,k}$ are assigned to each vertex such that $u$ and $v$ have different colors if $uv$ is…

Combinatorics · Mathematics 2016-05-10 Matthias Beck , Daniel Blado , Joseph Crawford , Taina Jean-Louis , Michael Young

We define a q-chromatic function on graphs, list some of its properties and provide some formulas in the class of general chordal graphs. Then we relate the q-chromatic function to the colored Jones function of knots. This leads to a…

Combinatorics · Mathematics 2007-05-23 Martin Loebl

In this note we introduce a family of polynomials on a matroid derived from chain Tutte polynomials which generalize the classic and ubiquitous characteristic polynomial. We show that the coefficients of these polynomials alternate and…

Combinatorics · Mathematics 2025-08-08 Gary Lazzaro , Max Wakefield , Jason Weiss

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…

Combinatorics · Mathematics 2014-04-15 Xueliang Li , Yongtang Shi , Martin Trinks

For each nonnegative integer $i$, let $a_i$ be the number of $i$-subsets of $V(G)$ that induce an acyclic subgraph of a given graph $G$. We define $A(G,x) = \sum_{i \geq 0} a_i x^i$ (the generating function for $a_i$) to be the acyclic…

Combinatorics · Mathematics 2022-02-07 Caroline Barton , Jason I. Brown , David A. Pike

We discuss the minimal number of vertices in a graph with a large chromatic number such that each ball of a fixed radius in it has a small chromatic number. It is shown that for every graph $G$ on $\sim((n+rc)/(c+rc))^{r+1}$ vertices such…

Combinatorics · Mathematics 2014-02-03 Ilya I. Bogdanov

Each graph and choice of a commutative ring gives rise to an associated graphical group. In this article, we introduce and investigate graph polynomials that enumerate conjugacy classes of graphical groups over finite fields according to…

Group Theory · Mathematics 2022-03-14 Tobias Rossmann

Let $G$ be a graph and $A$ the adjacency matrix of $G$. The permanental polynomial of $G$ is defined as $\mathrm{per}(xI-A)$. In this paper some of the results from a numerical study of the permanental polynomials of graphs are presented.…

Combinatorics · Mathematics 2015-01-29 Shunyi Liu , Jinjun Ren

The purpose of this paper is twofold. Firstly, we generalize the notion of characteristic polynomials of hyperplane and toric arrangements to those of certain abelian Lie group arrangements. Secondly, we give two interpretations for the…

Combinatorics · Mathematics 2019-12-30 Tan Nhat Tran , Masahiko Yoshinaga

The chromatic polynomial of a graph G counts the number of proper colorings of G. We give an affirmative answer to the conjecture of Read and Rota-Heron-Welsh that the absolute values of the coefficients of the chromatic polynomial form a…

Algebraic Geometry · Mathematics 2012-02-13 June Huh

The chromatic sum $\Sigma(G)$ of a graph $G$ is the smallest sum of colors among of proper coloring with the natural number. In this paper, we introduce a necessary condition for the existence of graph homomorphisms. Also, we present…

Combinatorics · Mathematics 2009-01-24 Meysam Alishahi , Ali Taherkhani

The chromatic functor of a simple graph is a functorization of the chromatic polynomial. M. Yoshinaga showed in \cite{Yoshinaga2015} that two finite graphs have isomorphic chromatic functors if and only if they have the same chromatic…

Combinatorics · Mathematics 2019-08-15 Ye Liu

We introduce joins of signed graphs and explore the chromatic number of the all-positive and all-negative joins. We prove an analogue to the theorem that the chromatic number of the join of two graphs equals the sum of their chromatic…

Combinatorics · Mathematics 2020-06-01 Amelia R. W. Mattern

We study the connections between link invariants, the chromatic polynomial, geometric representations of models of statistical mechanics, and their common underlying algebraic structure. We establish a relation between several algebras and…

Combinatorics · Mathematics 2010-09-15 Paul Fendley , Vyacheslav Krushkal
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