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Density matrices of graphs are combinatorial laplacians normalized to have trace one (Braunstein \emph{et al.} \emph{Phys. Rev. A,} \textbf{73}:1, 012320 (2006)). If the vertices of a graph are arranged as an array, then its density matrix…

Computational Complexity · Computer Science 2008-07-03 Roland Hildebrand , Stefano Mancini , Simone Severini

We completely classify the locally finite, infinite graphs with pure mapping class groups admitting a coarsely bounded generating set. We also study algebraic properties of the pure mapping class group: We establish a semidirect product…

Group Theory · Mathematics 2025-08-06 George Domat , Hannah Hoganson , Sanghoon Kwak

In this paper, a new concept in graphs namely well-f-coveredness is introduced. We characterize all graphs with such property, whose maximum induced forests are of boundary order. Also we prove several propositions concerning with obtaining…

Combinatorics · Mathematics 2021-06-01 Reza Jafarpour-Golzari

We prove that for any weakly convergent sequence of finite graphs with bounded vertex degrees, there exists a topological limit graphing.

Combinatorics · Mathematics 2007-05-23 Gabor Elek

A $k$-colouring (not necessarily proper) of vertices of a graph is called {\it acyclic}, if for every pair of distinct colours $i$ and $j$ the subgraph induced by the edges whose endpoints have colours $i$ and $j$ is acyclic. In the paper…

Discrete Mathematics · Computer Science 2016-08-24 Anna Fiedorowicz , Elżbieta Sidorowicz

We prove a new generalisation of Ramsey's theorem by showing that every $2$-edge-coloured graph with sufficiently large minimum degree contains a monochromatic induced subgraph whose minimum degree remains large. From this, we also derive…

Combinatorics · Mathematics 2026-04-17 Arnab Char , Ken-ichi Kawarabayashi , Lucas Picasarri-Arrieta

We say that an edge colouring breaks an automorphism if some edge is mapped to an edge of a different colour. We say that the colouring is distinguishing if it breaks every non-identity automorphism. We show that such colouring can be…

Combinatorics · Mathematics 2023-06-13 Jakub Kwaśny , Marcin Stawiski

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

The Divisibility Graph of a finite group $G$ has vertex set the set of conjugacy class lengths of non-central elements in $G$ and two vertices are connected by an edge if one divides the other. We determine the connected components of the…

Group Theory · Mathematics 2016-12-15 Adeleh Abdolghafourian , Mohammad A. Iranmanesh , Alice C. Niemeyer

Matrix partition problems generalize a number of natural graph partition problems, and have been studied for several standard graph classes. We prove that each matrix partition problem has only finitely many minimal obstructions for split…

Discrete Mathematics · Computer Science 2013-06-21 Tomás Feder , Pavol Hell , Oren Shklarsky

In this work, we investigate the relationship between $k$-repre\-sentable graphs and graphs representable by $k$-local words. In particular, we show that every graph representable by a $k$-local word is $(k+1)$-representable. A previous…

Combinatorics · Mathematics 2025-06-25 Philipp Böll , Pamela Fleischmann , Annika Huch , Jana Kreiß , Tim Löck , Kajus Park , Max Wiedenhöft

We construct tree-decompositions of graphs that distinguish all their k-blocks and tangles of order k, for any fixed integer k. We describe a family of algorithms to construct such decompositions, seeking to maximize their diversity subject…

Combinatorics · Mathematics 2014-04-25 Johannes Carmesin , Reinhard Diestel , Matthias Hamann , Fabian Hundertmark

Recently, Daligault, Rao and Thomass\'e asked in [3] if every hereditary class which is well-quasi-ordered by the induced subgraph relation is of bounded clique-width. There are two reasons why this questions is interesting. First, it…

Combinatorics · Mathematics 2015-08-26 Aistis Atminas , Vadim V. Lozin , Igor Razgon

Clustering algorithms for large networks typically use modularity values to test which partitions of the vertex set better represent structure in the data. The modularity of a graph is the maximum modularity of a partition. We consider the…

Combinatorics · Mathematics 2022-12-22 Colin McDiarmid , Fiona Skerman

An edge-coloring of a graph is called asymmetric if the only automorphism which preserves it is the identity. Lehner, Pil\'{s}niak, and Stawiski proved that all connected regular graphs except $K_2$ admit an asymmetric edge-coloring with…

Combinatorics · Mathematics 2021-07-21 Mariusz Grech , Andrzej Kisielewicz

Let $\Gamma$ be a finite, undirected, connected, simple graph. We say that a matching $\mathcal{M}$ is a \textit{permutable $m$-matching} if $\mathcal{M}$ contains $m$ edges and the subgroup of $\text{Aut}(\Gamma)$ that fixes the matching…

Combinatorics · Mathematics 2020-08-17 Alex Schaefer , Eric Swartz

Consider the following two ways to colour the vertices of a graph where the requirement that adjacent vertices get distinct colours is relaxed. A colouring has "defect" $d$ if each monochromatic component has maximum degree at most $d$. A…

Combinatorics · Mathematics 2018-03-22 David R. Wood

We show that, given an infinite cardinal $\mu$, a graph has colouring number at most $\mu$ if and only if it contains neither of two types of subgraph. We also show that every graph with infinite colouring number has a well-ordering of its…

Combinatorics · Mathematics 2018-07-05 Nathan Bowler , Johannes Carmesin , Péter Komjáth , Christian Reiher

Transductions are a general formalism for expressing transformations of graphs (and more generally, of relational structures) in logic. We prove that a graph class $\mathscr{C}$ can be $\mathsf{FO}$-transduced from a class of bounded-height…

Combinatorics · Mathematics 2022-04-01 Michał Pilipczuk , Patrice Ossona de Mendez , Sebastian Siebertz

Word-representable graphs are a class of graphs that can be represented by words, where edges and non-edges are determined by the alternation of letters in those words. Several papers in the literature have explored the…

Combinatorics · Mathematics 2025-08-22 Herman Z. Q. Chen , Humaira Hameed , Sergey Kitaev