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We present an algebraic characterization of perfect graphs, i.e., graphs for which the clique number and the chromatic number coincide for every induced subgraph. We show that a graph is perfect if and only if certain nonnegative…

Optimization and Control · Mathematics 2023-05-03 Amir Ali Ahmadi , Cemil Dibek

This chapter presents an introduction to graph colouring algorithms. The focus is on vertex-colouring algorithms that work for general classes of graphs with worst-case performance guarantees in a sequential model of computation. The…

Data Structures and Algorithms · Computer Science 2015-05-22 Thore Husfeldt

I will present a way to implement graph algorithms which is different from traditional methods. This work was motivated by the belief that some ideas from software engineering should be applied to graph algorithms. Re-usability of software…

Data Structures and Algorithms · Computer Science 2010-03-24 Marco Nissen

We define pure graphs, invertible graphs, and the notion of complementation of bicoloured graphs. The study of pure graphs is motivated by two conjectures about the transition systems of eulerian graphs and by the Cycle Double Cover…

Combinatorics · Mathematics 2007-05-23 François Genest

A proper labeling of a graph is an assignment of integers to some elements of a graph, which may be the vertices, the edges, or both of them, such that we obtain a proper vertex coloring via the labeling subject to some conditions. The…

Discrete Mathematics · Computer Science 2017-01-25 Ali Dehghan , Mohammad-Reza Sadeghi , Arash Ahadi

We introduce the computational problem of graphlet transform of a sparse large graph. Graphlets are fundamental topology elements of all graphs/networks. They can be used as coding elements to encode graph-topological information at…

Social and Information Networks · Computer Science 2020-09-02 Dimitris Floros , Nikos Pitsianis , Xiaobai Sun

Total variant of well known graph coloring game is considered. We determine exact values of total game chromatic number for some classes of graphs and show show the strategie for first player to win the game. We also show relation between…

Combinatorics · Mathematics 2012-10-30 Tomasz Bartnicki , Zofia Miechowicz

Recent work at the intersection of formal language theory and graph theory has explored graph grammars for graph modeling. However, existing models and formalisms can only operate on homogeneous (i.e., untyped or unattributed) graphs. We…

Social and Information Networks · Computer Science 2023-01-06 Satyaki Sikdar , Neil Shah , Tim Weninger

This work studies certain aspects of graphs embedded on surfaces. Initially, a colored graph model for a map of a graph on a surface is developed. Then, a concept analogous to (and extending) planar graph is introduced in the same spirit as…

Combinatorics · Mathematics 2007-05-23 Sostenes Lins

We study finite graphs embedded in oriented surfaces by associating a polynomial to it. The tools used in developing a theory of such graph polynomials are algebraic topological while the polynomial itself is inspired from ideas arising in…

Combinatorics · Mathematics 2022-05-02 Somnath Basu , Dhruv Bhasin , Siddhartha Lal , Siddhartha Patra

Modern methods of graph theory describe a graph up to isomorphism, which makes it difficult to create mathematical models for visualizing graph drawings on a plane. The topological drawing of the planar part of a graph allows representing…

Combinatorics · Mathematics 2024-08-01 Sergey Kurapov , Maxim Davidovsky

We propose a new approach for defining and searching clusters in graphs that represent real technological or transaction networks. In contrast to the standard way of finding dense parts of a graph, we concentrate on the structure of edges…

Combinatorics · Mathematics 2021-03-16 András London , Ryan R. Martin , András Pluhár

A total coloring of a graph $G$ is a coloring of its vertices and edges such that no adjacent vertices, edges, and no incident vertices and edges obtain the same color. An \emph{interval total $t$-coloring} of a graph $G$ is a total…

Discrete Mathematics · Computer Science 2010-10-15 P. A. Petrosyan , A. Yu. Torosyan , N. A. Khachatryan

We introduce a generalization of the well known graph (vertex) coloring problem, which we call the problem of \emph{component coloring of graphs}. Given a graph, the problem is to color the vertices using minimum number of colors so that…

Discrete Mathematics · Computer Science 2012-11-06 Ajit Diwan , Soumitra Pal , Abhiram Ranade

Many problems can be presented in an abstract form through a wide range of binary objects and relations which are defined over problem domain. In these problems, graphical demonstration of defined binary objects and solutions is the most…

Graphics · Computer Science 2016-03-24 Mohammadreza Ashouri , Ali Golshani , Dara Moazzmi , Mandana Ghasemi

We enumerate graph homomorphisms to quasi-complete graphs, i.e., graphs obtained from complete graphs by removing one edge. The source graphs are complete graphs, quasi-complete graphs, cycles, paths, wheels and broken wheels. These…

Combinatorics · Mathematics 2016-01-26 Pedro Lopes

The vertices of a $k$-token graph of a graph $G$ correspond to $k$ indistinguishable tokens placed on $k$ different vertices of $G$. Changing some conditions on both the nature of the tokens and the number of tokens allowed in each vertex…

Combinatorics · Mathematics 2026-04-07 Xiaodi Song , Cristina Dalfó , Miquel Àngel Fiol , Mercè Mora , Shenggui Zhang

Homomorphically full graphs are those for which every homomorphic image is isomorphic to a subgraph. We extend the definition of homomorphically full to oriented graphs in two different ways. For the first of these, we show that…

Discrete Mathematics · Computer Science 2024-02-14 Thomas Bellitto , Christopher Duffy , Gary MacGillivray

A graph is a mathematical object consisting of a set of vertices and a set of edges connecting vertices. Graphs can be drawn on paper in various ways, but until recently all published methods of drawing graphs have had undesirable…

Human-Computer Interaction · Computer Science 2014-05-22 Bob Blakley , G R Blakley , Sean M Blakley

A total dominating set in a graph is a set of vertices such that every vertex of the graph has a neighbor in the set. We introduce and study graphs that admit non-negative real weights associated to their vertices such that a set of…

Combinatorics · Mathematics 2015-05-12 Nina Chiarelli , Martin Milanic