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We prove that for every $t\in \mathbb{N}$ there is a constant $\gamma_t$ such that every graph with twin-width at most $t$ and clique number $\omega$ has chromatic number bounded by $2^{\gamma_t \log^{4t+3} \omega}$. In other words, we…

Combinatorics · Mathematics 2022-02-16 Michał Pilipczuk , Marek Sokołowski

We prove that the two-variable Tutte polynomial of hypergraphs can be defined via embedding activities. We also prove that embedding activities of hypergraphs yield a Crapo-style decomposition of $\mathbb{Z}^E$, thus generalizing Bernardi's…

Combinatorics · Mathematics 2024-08-16 Lilla Tóthmérész

Graph polynomials are polynomials assigned to graphs. Interestingly, they also arise in many areas outside graph theory as well. Many properties of graph polynomials have been widely studied. In this paper, we survey some results on the…

Combinatorics · Mathematics 2016-01-13 Xueliang Li , Yongtang Shi

We establish a relation between the Bollobas-Riordan polynomial of a ribbon graph with the relative Tutte polynomial of a plane graph obtained from the ribbon graph using its projection to the plane in a nontrivial way. Also we give a…

Combinatorics · Mathematics 2010-11-02 Clark Butler , Sergei Chmutov

A graph polynomial $P$ is weakly distinguishing if for almost all finite graphs $G$ there is a finite graph $H$ that is not isomorphic to $G$ with $P(G)=P(H)$. It is weakly distinguishing on a graph property $\mathcal{C}$ if for almost all…

Combinatorics · Mathematics 2020-10-21 Johann A. Makowsky , Vsevolod Rakita

The theory of graphons has proven to be a powerful tool in many areas of graph theory. In this paper, we introduce several foundational aspects of the theory of digraphons -- asymmetric two-variable functions that arise as limits of…

Combinatorics · Mathematics 2025-12-16 Jan Hladký , Petr Savický

The number of homomorphisms from a finite graph $F$ to the complete graph $K_n$ is the evaluation of the chromatic polynomial of $F$ at $n$. Suitably scaled, this is the Tutte polynomial evaluation $T(F;1-n,0)$ and an invariant of the cycle…

Combinatorics · Mathematics 2016-02-25 Andrew Goodall , Guus Regts , Lluis Vena

Let $G$ be a connected general graph. Let $f\colon V(G)\to \Z^+$ be a function. We show that $G$ satisfies the Tutte-type condition \[ o(G-S)\le f(S)\qquad\text{for all vertex subsets $S$}, \] if and only if it contains a colored…

Combinatorics · Mathematics 2015-12-17 Hongliang Lu , David G. L. Wang

We present a new edge selection heuristic and vertex ordering heuristic that together enable one to compute the Tutte polynomial of much larger sparse graphs than was previously doable. As a specific example, we are able to compute the…

Discrete Mathematics · Computer Science 2012-09-25 Michael Monagan

The fractional perfect b-matching polytope of an undirected graph G is the polytope of all assignments of nonnegative real numbers to the edges of G such that the sum of the numbers over all edges incident to any vertex v is a prescribed…

Combinatorics · Mathematics 2013-01-31 Roger E. Behrend

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

Using the definition of colouring of $2$-edge-coloured graphs derived from $2$-edge-coloured graph homomorphism, we extend the definition of chromatic polynomial to $2$-edge-coloured graphs. We find closed forms for the first three…

Combinatorics · Mathematics 2020-07-28 I. Beaton , D. Cox , C. Duffy , N. Zolkavich

In this paper we resolve the complexity of the isomorphism problem on all but finitely many of the graph classes characterized by two forbidden induced subgraphs. To this end we develop new techniques applicable for the structural and…

Discrete Mathematics · Computer Science 2014-11-10 Pascal Schweitzer

A b-coloring is a coloring of the vertices of a graph such that each color class contains a vertex that has a neighbor in all other color classes, and the b-chromatic number of a graph $G$ is the largest integer $k$ such that $G$ admits a…

Discrete Mathematics · Computer Science 2012-12-13 Chinh T. Hoàng , Frédéric Maffray , Meriem Mechebbek

In this paper, we find computational formulae for generalized characteristic polynomials of graph bundles. We show that the number of spanning trees in a graph is the partial derivative (at (0,1)) of the generalized characteristic…

Combinatorics · Mathematics 2008-07-03 Dongseok Kim , Hye Kyung Kim , Jaeun Lee

We introduce the concept of a relative Tutte polynomial of colored graphs. We show that this relative Tutte polynomial can be computed in a way similar to the classical spanning tree expansion used by Tutte in his original paper on this…

Combinatorics · Mathematics 2009-09-08 Yuanan Diao , Gabor Hetyei

Recently, M.\ Ab\'ert and T.\ Hubai studied the following problem. The chromatic measure of a finite simple graph is defined to be the uniform distribution on its chromatic roots. Ab\'ert and Hubai proved that for a Benjamini-Schramm…

Combinatorics · Mathematics 2015-12-10 Péter Csikvári , Péter E. Frenkel

In this paper, various kinds of invariants of directed graphs are summarized. In the first topic, the invariant w(G) for a directed graph G is introduced, which is primarily defined by S. Chen and X.M. Chen to solve a problem of weak…

Combinatorics · Mathematics 2015-01-16 Sheng Chen , Yilong Zhang

In this paper, we present some properties on chromatic polynomials of hypergraphs which do not hold for chromatic polynomials of graphs. We first show that chromatic polynomials of hypergraphs have all integers as their zeros and contain…

Combinatorics · Mathematics 2017-04-24 Ruixue Zhang , Fengming Dong

Entanglement is a complexity measure of digraphs that origins in fixed-point logics. Its combinatorial purpose is to measure the nested depth of cycles in digraphs. We address the problem of characterizing the structure of graphs of…

Computer Science and Game Theory · Computer Science 2009-04-13 Walid Belkhir