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The bidimensionality of a set of vertices $X$ in a graph $G$ is the maximum $k$ for which $G$ contains as a $X$-rooted minor the $(k \times k)$-grid. This notion allows for the following version of the Graph Minors Structure Theorem (GMST)…

Combinatorics · Mathematics 2026-05-27 Dimitrios M. Thilikos , Sebastian Wiederrecht

The Maximum Degree and Diameter Bounded Subgraph Problem (MaxDDBS) asks: given a host graph G, a bound on maximum degree \Delta, and a diameter D, what is the largest subgraph of the host graph with degree bounded by \Delta and diameter…

Combinatorics · Mathematics 2012-12-03 Sachi Hashimoto

The geometric thickness of a graph G is the minimum integer k such that there is a straight line drawing of G with its edge set partitioned into k plane subgraphs. Eppstein [Separating thickness from geometric thickness. In: Towards a…

Combinatorics · Mathematics 2007-05-23 Janos Barat , Jiri Matousek , David R. Wood

In this paper we consider the degree/diameter problem, namely, given natural numbers {\Delta} \geq 2 and D \geq 1, find the maximum number N({\Delta},D) of vertices in a graph of maximum degree {\Delta} and diameter D. In this context, the…

Combinatorics · Mathematics 2014-05-06 Ramiro Feria-Purón , Mirka Miller , Guillermo Pineda-Villavicencio

In this paper we give graphs with the largest known order for a given degree $\Delta$ and diameter $D$. The graphs are constructed from Moore bipartite graphs by replacement of some vertices by adequate structures. The paper also contains…

Combinatorics · Mathematics 2008-02-03 Francesc Comellas , J. Gómez

Let $G$ be a graph with edge set $E(G)$. Denote by $d_w$ the degree of a vertex $w$ of $G$. The sigma index of $G$ is defined as $\sum_{uv\in E(G)}(d_u-d_v)^2$. A connected graph of order $n$ and size $n+k-1$ is known as a connected…

Combinatorics · Mathematics 2022-07-12 Akbar Ali , Abeer M. Albalahi , Abdulaziz M. Alanazi , Akhlaq A. Bhatti , Amjad E. Hamza

The degree-diameter problem seeks to find the largest possible number of vertices in a graph having given diameter and given maximum degree. Very often the problem is studied for restricted families of graph such as vertex-transitive or…

Combinatorics · Mathematics 2018-04-13 Grahame Erskine , James Tuite

We consider the problem of coloring the squares of graphs of bounded maximum average degree, that is, the problem of coloring the vertices while ensuring that two vertices that are adjacent or have a common neighbour receive different…

Discrete Mathematics · Computer Science 2013-08-21 Marthe Bonamy , Benjamin Lévêque , Alexandre Pinlou

A connected graph $G$ with at least $2m+2n+2$ vertices is said to have property $E(m,n)$ if, for any two disjoint matchings $M$ and $N$ of size $m$ and $n$ respectively, $G$ has a perfect matching $F$ such that $M\subseteq F$ and $N\cap…

Combinatorics · Mathematics 2010-02-04 Qiuli Li , Heping Zhang

The degree-diameter problem consists of finding the maximum number of vertices $n$ of a graph with diameter $d$ and maximum degree $\Delta$. This problem is well studied, and has been solved for plane graphs of low diameter in which every…

Combinatorics · Mathematics 2024-01-23 Brandon Du Preez

By Brook's Theorem, every n-vertex graph of maximum degree at most Delta >= 3 and clique number at most Delta is Delta-colorable, and thus it has an independent set of size at least n/Delta. We give an approximate characterization of graphs…

Discrete Mathematics · Computer Science 2019-11-05 Zdenek Dvorak , Bernard Lidicky

We wish to bring attention to a natural but slightly hidden problem, posed by Erd\H{o}s and Ne\v{s}et\v{r}il in the late 1980s, an edge version of the degree--diameter problem. Our main result is that, for any graph of maximum degree…

The degree-diameter problem seeks to find the maximum possible order of a graph with a given (maximum) degree and diameter. It is known that graphs attaining the maximum possible value (the Moore bound) are extremely rare, but much activity…

Combinatorics · Mathematics 2016-05-03 Dominique Buset , Mourad El Amiri , Grahame Erskine , Hebert Pérez-Rosés , Mirka Miller

It is shown that any graph with maximum degree $\Delta$ in which the average degree of the induced subgraph on the set of all neighbors of any vertex exceeds $\frac{6k^2}{6k^2 + 1}\Delta + k + 6$ is either $(\Delta - k)$-colorable or…

Combinatorics · Mathematics 2012-10-02 Landon Rabern

The bondage number b(G) of a graph G is the smallest number of edges of G whose removal from G results in a graph having the domination number larger than that of G. We show that, for a graph G having the maximum vertex degree $\Delta(G)$…

Combinatorics · Mathematics 2016-04-25 Andrei Gagarin , Vadim Zverovich

A quadrangular embedding of a graph in a surface $\Sigma$, also known as a quadrangulation of $\Sigma$, is a cellular embedding in which every face is bounded by a $4$-cycle. A quadrangulation of $\Sigma$ is minimal if there is no…

Combinatorics · Mathematics 2021-06-28 Wenzhong Liu , M. N. Ellingham , Dong Ye

Erd\H{o}s determined the maximum size of a nonhamiltonian graph of order $n$ and minimum degree at least $k$ in 1962. Recently, Ning and Peng generalized. Erd\H{o}s' work and gave the maximum size $h(n,c,k)$ of graphs with prescribed order…

Combinatorics · Mathematics 2021-12-06 Leilei Zhang

A graph is $k$-degenerate if every subgraph has minimum degree at most $k$. We provide lower bounds on the size of a maximum induced 2-degenerate subgraph in a triangle-free planar graph. We denote the size of a maximum induced 2-degenerate…

Combinatorics · Mathematics 2018-02-21 Zdeněk Dvořák , Tom Kelly

Let $G$ be a $k$-degenerate graph of order $n.$ It is well-known that $G\ $has no more edges than $S_{n,k},$ the join of a complete graph of order $k$ and an independent set of order $n-k.$ In this note it is shown that $S_{n,k}$ is…

Combinatorics · Mathematics 2014-03-25 V. Nikiforov

Twin-width is a width parameter introduced by Bonnet, Kim, Thomass\'e and Watrigant [FOCS'20, JACM'22], which has many structural and algorithmic applications. We prove that the twin-width of every graph embeddable in a surface of Euler…

Combinatorics · Mathematics 2024-02-12 Daniel Kráľ , Kristýna Pekárková , Kenny Štorgel