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We present some results on the structure of line graphs of triangle-free graphs and a homogenization of the line graph of the universal homogeneous triangle-free graph in a finite relational language with arity 4. This result is relevant to…

Logic · Mathematics 2021-08-27 Andres Aranda

We prove local convergence results for the uniformly random, labelled or unlabelled, graphs from subcritical families. As an example special case, we prove Benjamini-Schramm convergence for the uniform random unlabelled tree. We introduce a…

Combinatorics · Mathematics 2016-11-28 Agelos Georgakopoulos , Stephan Wagner

An interval graph is considered improper if and only if it has a representation such that an interval contains another interval. Previously these have been investigated in terms of balance and minimal forbidden interval subgraphs for the…

Combinatorics · Mathematics 2015-05-28 Jeffrey J. Beyerl , Wayne Wallace

In the Online Delayed Connected H-Node-Deletion Problem, an unweighted graph is revealed vertex by vertex and it must remain free of any induced copies of a specific connected induced forbidden subgraph H at each point in time. To achieve…

Data Structures and Algorithms · Computer Science 2025-01-27 Hans-Joachim Böckenhauer , Melvin Jahn , Dennis Komm , Moritz Stocker

We consider the problem of partitioning a graph into a non-fixed number of non-overlapping subgraphs of maximum density. The density of a partition is the sum of the densities of the subgraphs, where the density of a subgraph is its average…

Computational Complexity · Computer Science 2022-02-17 Cristina Bazgan , Katrin Casel , Pierre Cazals

Graphs with bounded thinness were defined in 2007 as a generalization of interval graphs. In this paper we introduce the concept of proper thinness, such that graphs with bounded proper thinness generalize proper interval graphs. We study…

Discrete Mathematics · Computer Science 2023-04-04 Flavia Bonomo , Diego de Estrada

A string graph is the intersection graph of curves in the plane. Kratochv\'il previously showed the existence of infinitely many obstacles: graphs that are not string graphs but for which any edge contraction or vertex deletion produces a…

Combinatorics · Mathematics 2025-09-03 Maria Chudnovsky , David Eppstein , David Fischer

We present an easy structure theorem for graphs which do not admit an immersion of the complete graph. The theorem motivates the definition of a variation of tree decompositions based on edge cuts instead of vertex cuts which we call…

Combinatorics · Mathematics 2014-07-02 Paul Wollan

We study 3-random-like graphs, that is, sequences of graphs in which the densities of triangles and anti-triangles converge to 1/8. Since the random graph ${\mathcal G}_{n,1/2}$ is, in particular, 3-random-like, this can be viewed as a weak…

Combinatorics · Mathematics 2019-02-20 Dan Hefetz , Mykhaylo Tyomkyn

The simple connected graphs may be classified by their cycle composition (number and lengths of cycles). This work derives the counting series of the simple connected graphs that have cycles of unrestricted number and length, but no…

Combinatorics · Mathematics 2018-08-21 Richard J. Mathar

We consider large uniform labeled random graphs in different classes with prescribed decorations in their modular decomposition. Our main result is the estimation of the number of copies of every graph as an induced subgraph. As a…

Combinatorics · Mathematics 2023-10-25 Théo Lenoir

Let ${\rm Z}(G)$ and ${\rm gp}(G)$ be the zero forcing number and the general position number of a graph $G$, respectively. Known results imply that ${\rm gp}(T)\ge {\rm Z}(T) + 1$ holds for every nontrivial tree $T$. It is proved that the…

Combinatorics · Mathematics 2021-12-21 Hongbo Hua , Xinying Hua , Sandi Klavžar

A disconnected cut of a connected graph is a vertex cut that itself also induces a disconnected subgraph. The decision problem whether a graph has a disconnected cut is called Disconnected Cut. This problem is closely related to several…

Data Structures and Algorithms · Computer Science 2018-03-13 Barnaby Martin , Daniel Paulusma , Erik Jan van Leeuwen

We introduce the factorization graph of a finite group and study its connectedness and forbidden structures. We characterize all finite groups with connected factorization graphs and classify those with connected bipartite factorization…

Group Theory · Mathematics 2019-12-02 Mohammad Farrokhi Derakhshandeh Ghouchan , Ali Azimi

For a positive integer $n$, a graph with at least $n$ vertices is $n$-existentially closed or simply $n$-e.c. if for any set of vertices $S$ of size $n$ and any set $T\subseteq S$, there is a vertex $x\not\in S$ adjacent to each vertex of…

Combinatorics · Mathematics 2024-07-09 Andrea C. Burgess , Robert D. Luther , David A. Pike

Bounded infinite graphs are defined on the basis of natural physical requirements. When specialized to trees this definition leads to a natural conjecture that the average connectivity dimension of bounded trees cannot exceed two. We verify…

Condensed Matter · Physics 2009-11-07 Claudio Destri , Luca Donetti

The cut dominant of a graph is the unbounded polyhedron whose points are all those that dominate some convex combination of proper cuts. Minimizing a nonnegative linear function over the cut dominant is equivalent to finding a minimum…

Combinatorics · Mathematics 2015-02-27 Michele Conforti , Samuel Fiorini , Kanstantsin Pashkovich

Gy\'arf\'as and Sumner independently conjectured that for every tree $T$, the class of graphs not containing $T$ as an induced subgraph is $\chi$-bounded, that is, the chromatic numbers of graphs in this class are bounded above by a…

Combinatorics · Mathematics 2018-07-11 Alex Scott , Paul Seymour

Subgraph counting aims to count the occurrences of a subgraph template T in a given network G. The basic problem of computing structural properties such as counting triangles and other subgraphs has found applications in diverse domains.…

Distributed, Parallel, and Cluster Computing · Computer Science 2019-03-12 Langshi Chen , Jiayu Li , Ariful Azad , Lei Jiang , Madhav Marathe , Anil Vullikanti , Andrey Nikolaev , Egor Smirnov , Ruslan Israfilov , Judy Qiu

Twin-width is a structural width parameter introduced by Bonnet, Kim, Thomass\'e and Watrigant [FOCS 2020]. Very briefly, its essence is a gradual reduction (a contraction sequence) of the given graph down to a single vertex while…