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We compute a minimum degree threshold sufficient for 3-partite graphs to admit a fractional triangle decomposition. Together with recent work of Barber, K\"uhn, Lo, Osthus and Taylor, this leads to bounds for exact decompositions and in…

Combinatorics · Mathematics 2016-09-13 Flora C. Bowditch , Peter J. Dukes

Erd\H{o}s, Gallai, and Tuza posed the following problem: given an $n$-vertex graph $G$, let $\tau_1(G)$ denote the smallest size of a set of edges whose deletion makes $G$ triangle-free, and let $\alpha_1(G)$ denote the largest size of a…

Combinatorics · Mathematics 2015-03-26 Gregory J. Puleo

Every finite graph admits a \emph{simple (topological) drawing}, that is, a drawing where every pair of edges intersects in at most one point. However, in combination with other restrictions simple drawings do not universally exist. For…

Computational Geometry · Computer Science 2020-08-26 Michael Hoffmann , Chih-Hung Liu , Meghana M. Reddy , Csaba D. Tóth

In contrast with Kotzig's result that the line graph of a $3$-regular graph $X$ is Hamilton decomposable if and only if $X$ is Hamiltonian, we show that for each integer $k\geq 4$ there exists a simple non-Hamiltonian $k$-regular graph…

Combinatorics · Mathematics 2017-10-18 Darryn Bryant , Barbara Maenhaut , Benjamin R. Smith

An exact algorithm is presented for solving edge weighted graph partitioning problems. The algorithm is based on a branch and bound method applied to a continuous quadratic programming formulation of the problem. Lower bounds are obtained…

Optimization and Control · Mathematics 2009-12-10 William Hager , Dzung Phan , Hongchao Zhang

We prove that every graph which admits a tree-decomposition into finite parts has a rooted tree-decomposition into finite parts that is linked, tight and componental. As an application, we obtain that every graph without half-grid minor has…

Combinatorics · Mathematics 2024-05-14 Sandra Albrechtsen , Raphael W. Jacobs , Paul Knappe , Max Pitz

Let $f(n,k)$ be the minimum number of edges that must be removed from some complete geometric graph $G$ on $n$ points, so that there exists a tree on $k$ vertices that is no longer a planar subgraph of $G$. In this paper we show that…

We prove the following 30-year old conjecture of Gy\H{o}ri and Tuza: the edges of every $n$-vertex graph $G$ can be decomposed into complete graphs $C_1,\ldots,C_\ell$ of orders two and three such that $|C_1|+\cdots+|C_\ell|\le…

Combinatorics · Mathematics 2019-04-03 Daniel Král' , Bernard Lidický , Taísa L. Martins , Yanitsa Pehova

Given graphs $H_1, H_2$, a {red, blue}-coloring of the edges of a graph $G$ is a critical coloring if $G$ has neither a red $H_1$ nor a blue $ H_2$. A non-complete graph $G$ is $(H_1, H_2)$-co-critical if $G$ admits a critical coloring, but…

Combinatorics · Mathematics 2023-08-10 Gang Chen , Chenchen Ren , Zi-Xia Song

The present paper is the first one in the sequence of papers about a simple class of {\em framed $4$-graphs}; the goal of the present paper is to collect some well-known results on planarity and to reformulate them in the language of {\em…

Combinatorics · Mathematics 2014-02-10 Vassily Olegovich Manturov

A graph $G$ is $k$-$weighted-list-antimagic$ if for any vertex weighting $\omega\colon V(G)\to\mathbb{R}$ and any list assignment $L\colon E(G)\to2^{\mathbb{R}}$ with $|L(e)|\geq |E(G)|+k$ there exists an edge labeling $f$ such that…

Combinatorics · Mathematics 2023-06-22 Zhanar Berikkyzy , Axel Brandt , Sogol Jahanbekam , Victor Larsen , Danny Rorabaugh

For a graph $G$ and a parameter $k$, we call a vertex $k$-enabling if it belongs both to a clique of size $k$ and to an independent set of size $k$, and we call it $k$-excluding otherwise. Motivated by issues that arise in secret sharing…

Data Structures and Algorithms · Computer Science 2025-09-03 Uriel Feige , Ilia Pauzner

We demonstrate that for every positive integer $\Delta$, every K\_4-minor-free graph with maximum degree $\Delta$ admits an equitable coloring with k colors wherek $\ge$ ($\Delta$+3)/2. This bound is tight and confirms a conjecture by Zhang…

Combinatorics · Mathematics 2017-03-08 Rémi De Joannis de Verclos , Jean-Sébastien Sereni

We consider a the minimum k-way cut problem for unweighted graphs with a size bound s on the number of cut edges allowed. Thus we seek to remove as few edges as possible so as to split a graph into k components, or report that this requires…

Discrete Mathematics · Computer Science 2011-01-27 Ken-ichi Kawarabayashi , Mikkel Thorup

One interesting question is how a graph develops from some constrained random graph process, which is a fundamental mechanism in the formation and evolution of dynamic networks. The problem here is referred to the random $K_k$-removal…

Combinatorics · Mathematics 2022-01-07 Fang Tian , Zi-Long Liu , Xiang-Feng Pan

In this paper, we show that every $O(m)$-edge-connected simple graph $G$ of size divisible by $m$ with minimum degree at least $2^{O(m)}$ has an edge-decomposition into isomorphic copies of any given tree $T$ of size $m$. Moreover, the…

Combinatorics · Mathematics 2024-09-04 Morteza Hasanvand

An oriented graph is an orientation of a simple graph. In 2009, Keevash, K\"{u}hn and Osthus proved that every sufficiently large oriented graph $D$ of order $n$ with $(3n-4)/8$ is Hamiltonian. Later, Kelly, K\"{u}hn and Osthus showed that…

Combinatorics · Mathematics 2024-02-07 Jia Zhou , Zhilan Wang , Jin Yan

As a strengthening of Hadwiger's conjecture, Gerards and Seymour conjectured that every graph with no odd $K_t$ minor is $(t-1)$-colorable. We prove two weaker variants of this conjecture. Firstly, we show that for each $t \geq 2$, every…

Combinatorics · Mathematics 2019-06-17 Dong Yeap Kang , Sang-il Oum

The Weisfeiler-Leman procedure is a widely-used technique for graph isomorphism testing that works by iteratively computing an isomorphism-invariant coloring of vertex tuples. Meanwhile, a fundamental tool in structural graph theory, which…

Discrete Mathematics · Computer Science 2022-07-19 Sandra Kiefer , Daniel Neuen

A graph $G$ is called $C_4$-free if it does not contain the cycle $C_4$ as an induced subgraph. Hubenko, Solymosi and the first author proved (answering a question of Erd\H os) a peculiar property of $C_4$-free graphs: $C_4$ graphs with $n$…

Combinatorics · Mathematics 2015-09-22 A. Gyarfas , G. N. Sarkozy
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