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A central problem in extremal graph theory is to estimate, for a given graph $H$, the number of $H$-free graphs on a given set of $n$ vertices. In the case when $H$ is not bipartite, fairly precise estimates on this number are known. In…

Combinatorics · Mathematics 2017-10-13 Asaf Ferber , Gweneth Anne McKinley , Wojciech Samotij

Recently, Ali et al. posed several open problems concerning extremal graphs with respect to the ABS index. These problems involve characterizing graphs that attain the maximum ABS index within specific graph classes, including: connected…

Combinatorics · Mathematics 2025-12-30 Swathi Shetty , B. R. Rakshith , Sayinath Udupa N.

In this paper, we study two problems related to planar matchings in random bipartite graphs. First, we colour each edge of the complete bipartite graph $K_{n,n}$ uniformly randomly from amongst ${r}$ colours and show that if ${r}$ grows…

Probability · Mathematics 2023-01-13 Ghurumuruhan Ganesan

In 2003, Fischermann et al. considered the maximum size of \textit{uniquely-dominatable} graphs, graphs whose dominating number is realized only by a unique dominating set. They conjectured a size bound and provide a general graph…

Combinatorics · Mathematics 2025-11-04 Garrison Koch , Darren Narayan

An identifying code of a graph G is a dominating set C such that every vertex x of G is distinguished from all other vertices by the set of vertices in C that are at distance at most 1 from x. The problem of finding an identifying code of…

Discrete Mathematics · Computer Science 2011-02-25 Florent Foucaud , Eleonora Guerrini , Matjaz Kovse , Reza Naserasr , Aline Parreau , Petru Valicov

Motivated by the concept of well-covered graphs, we define a graph to be well-bicovered if every vertex-maximal bipartite subgraph has the same order (which we call the bipartite number). We first give examples of them, compare them with…

Combinatorics · Mathematics 2019-09-18 Wayne Goddard , Kirsti Kuenzel , Eileen Melville

The problem of determining the optimal minimum degree condition for a balanced bipartite graph on 2ms vertices to contain m vertex disjoint copies of K_{s,s} was solved by Zhao. Later Hladk\'y and Schacht, and Czygrinow and DeBiasio…

Combinatorics · Mathematics 2013-10-03 Andrzej Czygrinow , Louis DeBiasio

A graph is 1-planar if it admits a drawing in the plane such that each edge is crossed at most once. Let G be a bipartite 1-planar graph with partite sets X and Y. A 1-disk OX drawing of G is a 1-planar drawing such that all vertices of X…

Combinatorics · Mathematics 2025-07-29 Guiping Wang

The conjecture of Bollob\'as and Koml\'os, recently proved by B\"ottcher, Schacht, and Taraz [Math. Ann. 343(1), 175--205, 2009], implies that for any $\gamma>0$, every balanced bipartite graph on $2n$ vertices with bounded degree and…

Combinatorics · Mathematics 2011-07-28 Julia Böttcher , Peter Christian Heinig , Anusch Taraz

We study the problem of maximizing the number of independent sets in $n$-vertex $k$-chromatic $\ell$-connected graphs. First we consider maximizing the total number of independent sets in such graphs with $n$ sufficiently large, and for…

Combinatorics · Mathematics 2019-07-10 John Engbers , Lauren Keough , Taylor Short

Let $H$ be a fixed graph. Denote $f(n,H)$ to be the maximum number of edges not contained in any monochromatic copy of $H$ in a 2-edge-coloring of the complete graph $K_n$, and $ex(n,H)$ to be the {\it Tur\'an number} of $H$. An easy lower…

Combinatorics · Mathematics 2016-05-31 Jie Ma

Vizing's celebrated theorem asserts that any graph of maximum degree $\Delta$ admits an edge coloring using at most $\Delta+1$ colors. In contrast, Bar-Noy, Naor and Motwani showed over a quarter century that the trivial greedy algorithm,…

Data Structures and Algorithms · Computer Science 2019-04-22 Ilan Reuven Cohen , Binghui Peng , David Wajc

Differential Privacy is the gold standard in privacy-preserving data analysis. This paper addresses the challenge of producing a differentially edge-private vertex coloring. In this paper, we present two novel algorithms to approach this…

Data Structures and Algorithms · Computer Science 2026-02-17 Michael Xie , Jiayi Wu , Dung Nguyen , Aravind Srinivasan

A bipartite graph $G=(V,E)$ with $V=V_1\cup V_2$ is biregular if all the vertices of each stable set, $V_1$ and $V_2$, have the same degree, $r$ and $s$, respectively. This paper studies difference sets derived from both Abelian and…

Combinatorics · Mathematics 2024-04-09 G. Araujo-Pardo , C. Dalfó , M. A. Fiol , N. López

An edge-coloring of a graph $G$ with colors $1,\ldots,t$ is an \emph{interval $t$-coloring} if all colors are used, and the colors of edges incident to each vertex of $G$ are distinct and form an integer interval. It is well-known that…

Combinatorics · Mathematics 2019-12-04 Armen R. Davtyan , Gevorg M. Minasyan , Petros A. Petrosyan

Galvin showed that for all fixed $\delta$ and sufficiently large $n$, the $n$-vertex graph with minimum degree $\delta$ that admits the most independent sets is the complete bipartite graph $K_{\delta,n-\delta}$. He conjectured that except…

Combinatorics · Mathematics 2012-04-16 John Engbers , David Galvin

A lambda colouring (or $L(2,1)-$colouring) of a graph is an assignment of non-negative integers (with minimum assignment $0$) to its vertices such that the adjacent vertices must receive integers at least two apart and vertices at distance…

Combinatorics · Mathematics 2019-01-07 Kaushik Majumder , Ushnish Sarkar

The Bell colouring graph $\mathcal{B}(G)$ of a graph $G$ is the graph whose vertices are the partitions of the vertex set of $G$ into independent sets, with an edge between two partitions if and only if one can be obtained from the other by…

Combinatorics · Mathematics 2026-04-15 Brian Hearn

A conjecture of Alon, Krivelevich, and Sudakov states that, for any graph $F$, there is a constant $c_F > 0$ such that if $G$ is an $F$-free graph of maximum degree $\Delta$, then $\chi(G) \leq c_F \Delta / \log\Delta$. Alon, Krivelevich,…

Combinatorics · Mathematics 2022-01-25 James Anderson , Anton Bernshteyn , Abhishek Dhawan

In 2009, Kong, Wang, and Lee introduced the problem of finding the edge-balanced index sets ($EBI$) of complete bipartite graphs $K_{m,n}$, where they examined the cases $n=1$, $2$, $3$, $4$, $5$ and the case $m=n$. Since then the problem…

Combinatorics · Mathematics 2015-09-08 Ha Dao , Hung Hua , Michael Ngo , Christopher Raridan
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