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A {\it rainbow matching} in an edge-colored graph is a matching in which all the edges have distinct colors. Wang asked if there is a function f(\delta) such that a properly edge-colored graph G with minimum degree \delta and order at least…

Combinatorics · Mathematics 2011-08-15 Jennifer Diemunsch , Michael Ferrara , Casey Moffatt , Florian Pfender , Paul S. Wenger

An edge-colored graph $G$, where adjacent edges may be colored the same, is rainbow connected if any two vertices of $G$ are connected by a path whose edges have distinct colors. The rainbow connection number $rc(G)$ of a connected graph…

Combinatorics · Mathematics 2011-05-27 Xueliang Li , Sujuan Liu

An edge-colored graph $G$ is rainbow connected, if any two vertices are connected by a path whose edges have distinct colors. The rainbow connection number of a connected graph $G$, denoted $rc(G)$, is the smallest number of colors that are…

Combinatorics · Mathematics 2011-10-27 Xueliang Li , Mengmeng Liu , Ingo Schiermeyer

Balogh, Bar\'at, Gerbner, Gy\'arf\'as, and S\'ark\"ozy proposed the following conjecture. Let $G$ be a graph on $n$ vertices with minimum degree at least $3n/4$. Then for every $2$-edge-colouring of $G$, the vertex set $V(G)$ may be…

Combinatorics · Mathematics 2015-02-27 Shoham Letzter

Given graphs $F$ and $H$, the generalized rainbow Tur\'an number $\text{ex}(n,F,\text{rainbow-}H)$ is the maximum number of copies of $F$ in an $n$-vertex graph with a proper edge-coloring that contains no rainbow copy of $H$. B. Janzer…

Combinatorics · Mathematics 2021-09-23 József Balogh , Michelle Delcourt , Emily Heath , Lina Li

Bondy and Vince proved that a graph of minimum degree at least three contains two cycles whose lengths differ by one or two, which was conjectured by Erd\H{o}s. Gao, Li, Ma and Xie gave an average degree counterpart of Bondy-Vince's result,…

Combinatorics · Mathematics 2025-06-11 Binlong Li , Yufeng Pan , Lingjuan Shi

In this paper, we prove a conjecture of Aharoni and Howard on the existence of rainbow (transversal) matchings in sufficiently large families $\mathcal F_1,\ldots, \mathcal F_s$ of tuples in $\{1,\ldots, n\}^k$, provided $s\ge 470.$

Combinatorics · Mathematics 2020-10-21 Sergei Kiselev , Andrey Kupavskii

A path in an edge-colored graph is said to be rainbow if no color repeats on it. An edge-colored graph is said to be rainbow $k$-connected if every pair of vertices is connected by $k$ internally disjoint rainbow paths. The rainbow…

Combinatorics · Mathematics 2025-11-19 Igor Araujo , Kareem Benaissa , Richard Bi , Sean English , Shengan Wu , Pai Zheng

In an edge-colored graph $(G,c)$, let $d^c(v)$ denote the number of colors on the edges incident with a vertex $v$ of $G$ and $\delta^c(G)$ denote the minimum value of $d^c(v)$ over all vertices $v\in V(G)$. A cycle of $(G,c)$ is called…

Combinatorics · Mathematics 2020-07-29 Xiaozheng Chen , Xueliang Li

Let $G$ be an edge-coloured graph. The minimum colour degree $ \delta^c(G) $ of $G$ is the largest integer $k$ such that, for every vertex $v$, there are at least $k$ distinct colours on edges incident to $v$. We say that $G$ is properly…

Combinatorics · Mathematics 2013-12-11 Allan Lo

Erd\"os conjectured that if $G$ is a triangle free graph of chromatic number at least $k\geq 3$, then it contains an odd cycle of length at least $k^{2-o(1)}$ \cite{sudakovverstraete, verstraete}. Nothing better than a linear bound…

Discrete Mathematics · Computer Science 2008-09-11 Ajit A. Diwan , Sreyash Kenkre , Sundar Vishwanathan

Resolving a conjecture of Bollob\'{a}s and Erd\H{o}s, Gy\'{a}rf\'{a}s proved that every graph $G$ of chromatic number $k+1\geq 3$ contains cycles of $\lfloor\frac{k}{2}\rfloor$ distinct odd lengths. We strengthen this prominent result by…

Combinatorics · Mathematics 2021-04-07 Jun Gao , Qingyi Huo , Jie Ma

We prove that a random graph $G(n,p)$, with $p$ above the Hamiltonicity threshold, is typically such that for any $r$-colouring of its edges there exists a Hamilton cycle with at least $(2/(r+ 1)-o(1))n$ edges of the same colour. This…

Combinatorics · Mathematics 2021-04-22 Lior Gishboliner , Michael Krivelevich , Peleg Michaeli

One of the most famous results in the theory of random graphs establishes that the threshold for Hamiltonicity in the Erdos-Renyi random graph G_{n,p} is around p ~ (log n + log log n) / n. Much research has been done to extend this to…

Combinatorics · Mathematics 2011-01-04 Alan Frieze , Po-Shen Loh

A graph G is (a:b)-colorable if there exists an assignment of b-element subsets of {1,...,a} to vertices of G such that sets assigned to adjacent vertices are disjoint. We show that every planar graph without cycles of length 4 or 5 is…

Combinatorics · Mathematics 2019-07-16 Zdeněk Dvořák , Xiaolan Hu

Given a finite family $\mathcal{F}$ of graphs, we say that a graph $G$ is "$\mathcal{F}$-free" if $G$ does not contain any graph in $\mathcal{F}$ as a subgraph. A vertex-colored graph $H$ is called "rainbow" if no two vertices of $H$ have…

Combinatorics · Mathematics 2024-06-18 Manu Basavaraju , L. Sunil Chandran , Mathew C. Francis , Karthik Murali

Let $HP_{n,m,k}$ be drawn uniformly from all $k$-uniform, $k$-partite hypergraphs where each part of the partition is a disjoint copy of $[n]$. We let $HP^{(\k)}_{n,m,k}$ be an edge colored version, where we color each edge randomly from…

Combinatorics · Mathematics 2014-01-29 Deepak Bal , Alan Frieze

In 2022, Gao, Huo, Liu, and Ma proved that every graph with minimum degree at least $k+1$ contains $k$ admissible cycles, where a set of $k$ cycles is said to be admissible if their lengths form an arithmetic progression with common…

Combinatorics · Mathematics 2026-04-03 Jifu Lin

Given an edge-colored graph $G$, we denote the number of colors as $c(G)$, and the number of edges as $e(G)$. An edge-colored graph is rainbow if no two edges share the same color. A proper $mK_3$ is a vertex disjoint union of $m$ rainbow…

Combinatorics · Mathematics 2024-02-29 Jürgen Kritschgau , tahda queer , Cyrus Young , Wohua Zhou

It is conjectured that every edge-colored complete graph $G$ on $n$ vertices satisfying $\Delta^{mon}(G)\leq n-3k+1$ contains $k$ vertex-disjoint properly edge-colored cycles. We confirm this conjecture for $k=2$, prove several additional…

Combinatorics · Mathematics 2017-08-30 Ruonan Li , Hajo Broersma , Shenggui Zhang
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