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We consider the task of drawing a graph on multiple horizontal layers, where each node is assigned a layer, and each edge connects nodes of different layers. Known algorithms determine the orders of nodes on each layer to minimize crossings…

Data Structures and Algorithms · Computer Science 2025-03-03 Alexander Dobler , Jakob Roithinger

Let $\mathcal{A}$ be a set of positive numbers. A graph $G$ is called an $\mathcal{A}$-embeddable graph in $\mathbb{R}^d$ if the vertices of $G$ can be positioned in $\mathbb{R}^d$ so that the distance between endpoints of any edge is an…

Computational Complexity · Computer Science 2017-10-17 Mikhail Tikhomirov

Higher dimensional graphs can be used to colour two-dimensional geometric graphs. If G the boundary of a three dimensional graph H for example, we can refine the interior until it is colourable with 4 colours. The later goal is achieved if…

Combinatorics · Mathematics 2014-12-23 Oliver Knill

We call a finite undirected graph minimally k-matchable if it has at least k distinct perfect matchings but deleting any edge results in a graph which has not. An odd subdivision of some graph G is any graph obtained by replacing every edge…

Combinatorics · Mathematics 2016-08-05 Gasper Fijavz , Matthias Kriesell

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

Given a family $\mathcal{H}$ of graphs, a graph $G$ is called $\mathcal{H}$-universal if $G$ contains every graph of $\mathcal{H}$ as a subgraph. Following the extensive research on universal graphs of small size for bounded-degree graphs,…

Combinatorics · Mathematics 2023-09-12 Peter Allen , Julia Böttcher , Anita Liebenau

We introduce a method to embed edge-colored graphs into families of expander graphs, which generalizes a framework developed by Dragani\'c, Krivelevich, and Nenadov (2022). As an application, we show that each family of sufficiently…

Combinatorics · Mathematics 2025-01-27 Ben Lund , Chuandong Xu

Graph edit distance (GED) is a powerful and flexible graph matching paradigm that can be used to address different tasks in structural pattern recognition, machine learning, and data mining. In this paper, some new binary linear programming…

Data Structures and Algorithms · Computer Science 2015-05-22 Julien Lerouge , Zeina Abu-Aisheh , Romain Raveaux , Pierre Héroux , Sébastien Adam

Let $G(V, E)$ be a simple connected graph, with $|E| = \epsilon.$ In this paper, we define an edge-set graph $\mathcal G_G$ constructed from the graph $G$ such that any vertex $v_{s,i}$ of $\mathcal G_G$ corresponds to the $i$-th…

General Mathematics · Mathematics 2023-07-19 Johan Kok , N. K. Sudev , K. P. Chithra

A sum graph is a finite simple graph whose vertex set is labeled with distinct positive integers such that two vertices are adjacent if and only if the sum of their labels is itself another label. The spum of a graph $G$ is the minimum…

Combinatorics · Mathematics 2022-04-26 Rupert Li

A graph H is a square root of a graph G if G can be obtained from H by adding an edge between any two vertices in H that are of distance 2. The Square Root problem is that of deciding whether a given graph admits a square root. This problem…

Data Structures and Algorithms · Computer Science 2016-08-30 Manfred Cochefert , Jean-François Couturier , Petr A. Golovach , Dieter Kratsch , Daniël Paulusma , Anthony Stewart

A proper vertex colouring of a graph is \emph{nested} if the vertices of each of its colour classes can be ordered by inclusion of their open neighbourhoods. Through a relation to partially ordered sets, we show that the nested chromatic…

Combinatorics · Mathematics 2013-06-04 David Cook

A mixed graph $G$ can contain both (undirected) edges and arcs (directed edges). Here we derive an improved Moore-like bound for the maximum number of vertices of a mixed graph with diameter at least three. Moreover, a complete enumeration…

Combinatorics · Mathematics 2018-04-26 C. Dalfó , M. A. Fiol , N. López

Edge lengths of a graph are called flexible if there exist infinitely many non-congruent realizations of the graph in the plane satisfying these edge lengths. It has been shown recently that a graph has flexible edge lengths if and only if…

Combinatorics · Mathematics 2021-02-05 Georg Grasegger , Jan Legerský , Josef Schicho

Graph Neural Network (GNN) research has produced strategies to modify a graph's edges using gradients from a trained GNN, with the goal of network design. However, the factors which govern gradient-based editing are understudied, obscuring…

Machine Learning · Computer Science 2023-10-27 Donald Loveland , Rajmonda Caceres

We show that for all $n \equiv 0 \pmod{6}$, $n \geq 18$, there is an orientable triangular embedding of the octahedral graph on $n$ vertices that can be augmented with handles to produce a genus embedding of the complete graph of the same…

Combinatorics · Mathematics 2024-12-24 Timothy Sun

A graph {\it has cutwidth at most 2} if one can number its vertices by $1,\ldots n$ so that for every $i=1,\ldots,n-1$ there are at most 2 edges $(u,v)$ such that $u\le i<v$. A characterization of graphs having cutwidth at most 2 in terms…

Combinatorics · Mathematics 2019-12-13 Nadya Khoroshavkina

In this note, we fix a graph $H$ and ask into how many vertices can each vertex of a clique of size $n$ can be "split" such that the resulting graph is $H$-free. Formally: A graph is an $(n,k)$-graph if its vertex sets is a pairwise…

Combinatorics · Mathematics 2025-02-05 Maria Axenovich , Ryan R. Martin

We introduce and study the problem of constructing geometric graphs that have few vertices and edges and that are universal for planar graphs or for some sub-class of planar graphs; a geometric graph is \emph{universal} for a class…

Combinatorics · Mathematics 2020-06-22 Fabrizio Frati , Michael Hoffmann , Csaba D. Tóth

A graph is said to be orthogonalisable if the set of real symmetric matrices whose off-diagonal pattern is prescribed by its edges contains an orthogonal matrix. We determine some necessary and some sufficient conditions on the sizes of the…

Combinatorics · Mathematics 2025-06-16 Rupert H. Levene , Polona Oblak , Helena Šmigoc