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This paper continues a series of papers investigating the following question: which hereditary graph classes have bounded treewidth? We call a graph $t$-clean if it does not contain as an induced subgraph the complete graph $K_t$, the…

Combinatorics · Mathematics 2024-09-05 Tara Abrishami , Maria Chudnovsky , Sepehr Hajebi , Sophie Spirkl

We characterize clique trees of a chordal graph in their relation to simplicial vertices and perfect sequences of maximal cliques. We investigate boundary cliques defined by Shibata and clarify their relation to endpoints of clique trees.…

Discrete Mathematics · Computer Science 2007-05-23 Hisayuki Hara , Akimichi Takemura

We prove that every class of graphs $\mathscr C$ that is monadically stable and has bounded twin-width can be transduced from some class with bounded sparse twin-width. This generalizes analogous results for classes of bounded linear…

Logic in Computer Science · Computer Science 2022-09-20 Jakub Gajarský , Michał Pilipczuk , Szymon Toruńczyk

In this article we present the idea of clique ceiling numbers of the vertices of a given graph that has a universal vertex. We follow up with a polynomial-time algorithm to compute an upper bound for the clique number of such a graph using…

Combinatorics · Mathematics 2019-06-04 R. Dharmarajan , D. Ramachandran

In this paper, we introduce a class of graphs which we call average hereditary graphs. Many graphs that occur in the usual graph theory applications belong to this class of graphs. Many popular types of graphs fall under this class, such as…

Discrete Mathematics · Computer Science 2025-08-11 Syed Mujtaba Hassan , Shahid Hussain

A clique transversal in a graph is a set of vertices intersecting all maximal cliques. The problem of determining the minimum size of a clique transversal has received considerable attention in the literature. In this paper, we initiate the…

Combinatorics · Mathematics 2024-08-14 Martin Milanič , Yushi Uno

We prove that any class of graphs with linear neighborhood complexity has bounded improper odd chromatic number. As a result, if $\mathcal{G}$ is the class of all circle graphs, or if $\mathcal{G}$ is any class with bounded twin-width,…

Combinatorics · Mathematics 2026-02-12 James Davies , Meike Hatzel , Kolja Knauer , Rose McCarty , Torsten Ueckerdt

We investigate the number of maximal cliques, i.e., cliques that are not contained in any larger clique, in three network models: Erd\H{o}s-R\'enyi random graphs, inhomogeneous random graphs (also called Chung-Lu graphs), and geometric…

Combinatorics · Mathematics 2024-11-27 Thomas Bläsius , Maximillian Katzmann , Clara Stegehuis

We consider the problem of clique coloring, that is, coloring the vertices of a given graph such that no (maximal) clique of size at least two is monocolored. It is known that interval graphs are $2$-clique colorable. In this paper we prove…

Combinatorics · Mathematics 2023-04-04 Flavia Bonomo , María Pía Mazzoleni , Maya Stein

A population of complete subgraphs or cliques in a network evolving via duplication-divergence is considered. We find that a number of cliques of each size scales linearly with the size of the network. We also derive a clique population…

Molecular Networks · Quantitative Biology 2009-11-11 I. Ispolatov , P. L. Krapivsky , I. Mazo , A. Yuryev

Here in particular, we give a characterization of Quasi-line Graphs in terms of forbidden induced subgraphs. In general, we prove a necessary and sufficient condition for a graph to be a union of two cliques.

Combinatorics · Mathematics 2015-10-26 Medha Dhurandhar

We prove that a hereditary graph class $\mathcal{G}$ defined by finitely many excluded induced subgraphs has bounded tree-$\alpha$ if and only if it is "$(\mathrm{tw},\omega)$-bounded" (that is, for all $t\in \mathbb N$, the class of all…

Combinatorics · Mathematics 2026-05-05 Sepehr Hajebi , Sophie Spirkl

We present a class of (diamond, even hole)-free graphs with no clique cutset that has unbounded rank-width. In general, even-hole-free graphs have unbounded rank-width, because chordal graphs are even-hole-free. A.A. da Silva, A. Silva and…

Discrete Mathematics · Computer Science 2023-06-22 Isolde Adler , Ngoc Khang Le , Haiko Müller , Marko Radovanović , Nicolas Trotignon , Kristina Vušković

We prove that the joint embedding property is undecidable for hereditary graph classes, via a reduction from the tiling problem. The proof is then adapted to show the undecidability of the joint homomorphism property as well.

Logic · Mathematics 2023-06-22 Samuel Braunfeld

A clique-coloring of a given graph $G$ is a coloring of the vertices of $G$ such that no maximal clique of size at least two is monocolored. The clique-chromatic number of $G$ is the least number of colors for which $G$ admits a…

Combinatorics · Mathematics 2019-09-17 Behnaz Omoomi , Maryam Taleb

A clique colouring of a graph is a colouring of the vertices such that no maximal clique is monochromatic (ignoring isolated vertices). The least number of colours in such a colouring is the clique chromatic number. Given $n$ points $x_1,…

Combinatorics · Mathematics 2018-12-04 Colin McDiarmid , Dieter Mitsche , Pawel Pralat

We prove that the directed treewidth, DAG-width and Kelly-width of a digraph are bounded above by its circumference plus one.

Combinatorics · Mathematics 2014-01-14 Shiva Kintali

The clique chromatic number of a graph is the minimum number of colours needed to colour its vertices so that no inclusion-wise maximal clique which is not an isolated vertex is monochromatic. We show that every graph of maximum degree…

Combinatorics · Mathematics 2021-09-13 Gwenaël Joret , Piotr Micek , Bruce Reed , Michiel Smid

If $\Gamma$ is a graph for which every edge is in exactly one clique of order $\omega$, then one can form a new graph with vertex set equal to these cliques. This is a generalization of the line graph of $\Gamma$. We discover many general…

Combinatorics · Mathematics 2025-02-26 Robert R. Petro , Connor M. Phillips

The class of quasi-chain graphs is an extension of the well-studied class of chain graphs. This latter class enjoys many nice and important properties, such as bounded clique-width, implicit representation, well-quasi-ordering by induced…

Combinatorics · Mathematics 2021-04-12 Bogdan Alecu , Aistis Atminas , Vadim Lozin , Dmitriy Malyshev