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We establish a sharp upper bound on the number of properly $3$-edge-colored $K_4$'s in graphs with $R$ red, $G$ green and $B$ blue edges. We give a computer-free flag-algebra proof of this bound, and we also convert our proof into a…

Combinatorics · Mathematics 2026-02-18 József Balogh , Peter Bradshaw , Ramon I. Garcia , Bernard Lidický

A graph is $F$-saturated if it is $F$-free but the addition of any edge creates a copy of $F$. In this paper we study the quantity $\mathrm{sat}(n, H, F)$ which denotes the minimum number of copies of $H$ that an $F$-saturated graph on $n$…

Combinatorics · Mathematics 2018-10-16 Jürgen Kritschgau , Abhishek Methuku , Michael Tait , Craig Timmons

The rainbow connection number, rc(G), of a connected graph G is the minimum number of colours needed to colour its edges, so that every pair of its vertices is connected by at least one path in which no two edges are coloured the same. In…

Combinatorics · Mathematics 2012-09-12 Manu Basavaraju , L. Sunil Chandran , Deepak Rajendraprasad , Arunselvan Ramaswamy

A path in an edge-colored graph $G$, where adjacent edges may be colored the same, is a rainbow path if every two edges of it receive distinct colors. The rainbow connection number of a connected graph $G$, denoted by $rc(G)$, is the…

Combinatorics · Mathematics 2014-07-23 Qingqiong Cai , Xueliang Li , Yan Zhao

A $\rho$-mean coloring of a graph is a coloring of the edges such that the average number of colors incident with each vertex is at most $\rho$. For a graph $H$ and for $\rho \geq 1$, the {\em mean Ramsey-Tur\'an number} $RT(n,H,\rho-mean)$…

Combinatorics · Mathematics 2007-05-23 Raphael Yuster

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 by $rc(G)$, is the smallest number of colors that…

Combinatorics · Mathematics 2011-10-07 Jiuying Dong , Xueliang Li

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

Combinatorics · Mathematics 2012-10-03 Alan Frieze , Charalampos E. Tsourakakis

The closed neighbourhood $N[v]$ of a vertex $v$ of a graph $G$, consisting of at least one vertex from all colour classes with respect to a proper colouring of $G$, is called a rainbow neighbourhood in $G$. The minimum number of vertices…

General Mathematics · Mathematics 2017-11-13 Johan Kok , Sudev Naduvath , Eunice Gogo Mphako-Banda

Let $G$ be a fixed graph and let ${\mathcal F}$ be a family of graphs. A subgraph $J$ of $G$ is ${\mathcal F}$-saturated if no member of ${\mathcal F}$ is a subgraph of $J$, but for any edge $e$ in $E(G)-E(J)$, some element of ${\mathcal…

Combinatorics · Mathematics 2014-08-15 Michael Ferrara , Michael S. Jacobson , Florian Pfender , Paul S. Wenger

For a fixed graph $F$, the rainbow Tur\'an number $\mathrm{ex^*}(n,F)$ is the largest number of edges possible in an $n$-vertex graph which admits a rainbow-$F$-free proper edge-coloring. We focus on the rainbow Tur\'an numbers of trees…

Combinatorics · Mathematics 2025-12-19 Anastasia Halfpap

In a graph $G$ with a given edge colouring, a rainbow path is a path all of whose edges have distinct colours. The minimum number of colours required to colour the edges of $G$ so that every pair of vertices is joined by at least one…

Combinatorics · Mathematics 2012-12-10 Annika Heckel , Oliver Riordan

Let $H$ be a fixed graph. A graph $G$ is called {\it $H$-saturated} if $H$ is not a subgraph of $G$ but the addition of any missing edge to $G$ results in an $H$-subgraph. The {\it saturation number} of $H$, denoted $sat(n,H)$, is the…

Combinatorics · Mathematics 2024-04-19 Wen-Han Zhu , Rong-Xia Hao , Zhen He

Let $G = (V, E)$ be an $n$-vertex edge-colored graph. In 2013, H. Li proved that if every vertex $v \in V$ is incident to at least $(n+1)/2$ distinctly colored edges, then $G$ admits a rainbow triangle. We prove that the same hypothesis…

Combinatorics · Mathematics 2021-02-24 Andrzej Czygrinow , Theodore Molla , Brendan Nagle , Roy Oursler

Given a graph $F$, the Tur\'{a}n number ${\rm ex}(n,F)$ is the maximum number of edges in any $n$-vertex $F$-free graph. The odd-ballooning of $F$, denoted by $F^{o}$, is a graph obtained by replacing each edge of $F$ with an odd cycle,…

Combinatorics · Mathematics 2025-08-19 Longfei Fang , Xueyi Huang , Huiqiu Lin , Jinlong Shu

Motivated by the Ruzsa-Szemer\'{e}di problem, Imolay, Karl, Nagy, and V\'{a}li studied a variant of Tur\'{a}n number $ex_F(n,G)$ (called the $F$-multicolor Tur\'{a}n number of $G$), defined as the maximum number of edge-disjoint copies of…

Combinatorics · Mathematics 2026-03-27 Ping Li , Yang Yang

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

An edge-colored graph is called \textit{rainbow graph} if all the colors on its edges are distinct. Given a positive integer $n$ and a graph $G$, the \textit{anti-Ramsey number} $ar(n,G)$ is defined to be the minimum number of colors $r$…

Combinatorics · Mathematics 2025-06-10 Hongliang Lu , Xinyue Luo , Xinxin Ma

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 by $rc(G)$, is the smallest number of colors that…

Computational Complexity · Computer Science 2011-11-15 Xiaolong Huang , Xueliang Li , Yongtang Shi

For two given graphs $G$ and $F$, a graph $ H$ is said to be weakly $ (G, F) $-saturated if $H$ is a spanning subgraph of $ G$ which has no copy of $F$ as a subgraph and one can add all edges in $ E(G)\setminus E(H)$ to $ H$ in some order…

Combinatorics · Mathematics 2024-03-12 Olga Kalinichenko , Meysam Miralaei , Ali Mohammadian , Behruz Tayfeh-Rezaie

A path in an edge-colored graph $G$, where adjacent edges may have the same color, is called a rainbow path if no two edges of the path are colored the same. The rainbow connection number $rc(G)$ of $G$ is the minimum integer $i$ for which…

Combinatorics · Mathematics 2015-03-17 Hengzhe Li , Xueliang Li , Sujuan Liu