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Let t be an integer, f(n) a function, and H a graph. Define the t-Ramsey-Tur\'an number of H, RT_t(n, H, f(n)), to be the maximum number of edges in an n-vertex, H-free graph G where f(n) is larger than the maximum number of vertices in a…

Combinatorics · Mathematics 2013-07-29 József Balogh , John Lenz

Let r be an integer, f(n) a function, and H a graph. Introduced by Erd\H{o}s, Hajnal, S\'{o}s, and Szemer\'edi, the r-Ramsey-Tur\'{a}n number of H, RT_r(n, H, f(n)), is defined to be the maximum number of edges in an n-vertex, H-free graph…

Combinatorics · Mathematics 2013-07-29 József Balogh , John Lenz

Let $s$ be an integer, $f=f(n)$ a function, and $H$ a graph. Define the Ramsey-Tur\'an number $RT_s(n,H, f)$ as the maximum number of edges in an $H$-free graph $G$ of order $n$ with $\alpha_s(G) < f$, where $\alpha_s(G)$ is the maximum…

Combinatorics · Mathematics 2015-11-17 Patrick Bennett , Andrzej Dudek

Given graphs $H_1,\ldots, H_k$, a graph $G$ is $(H_1,\ldots, H_k)$-free if there is a $k$-edge-colouring $\phi:E(G)\rightarrow [k]$ with no monochromatic copy of $H_i$ with edges of colour $i$ for each $i\in[k]$. Fix a function $f(n)$, the…

Combinatorics · Mathematics 2018-03-14 Jaehoon Kim , Younjin Kim , Hong Liu

Given a graph $H$ and a function $f(n)$, the Ramsey-Tur\'an number $RT(n,H,f(n))$ is the maximum number of edges in an $n$-vertex $H$-free graph with independence number at most $f(n)$. For $H$ being a small clique, many results about…

Combinatorics · Mathematics 2023-08-04 József Balogh , Ce Chen , Grace McCourt , Cassie Murley

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

Let $f(n)$ be a function and $L$ be a graph. Denote by $RT(n,L,f(n))$ the maximum number of edges of an $L$-free graph on $n$ vertices with independence number less than $f(n)$. Erd\H os and S\'os asked if $RT\left(n, K_5, c\sqrt{n}\right)…

Combinatorics · Mathematics 2015-04-08 József Balogh , Ping Hu , Miklós Simonovits

We study the generalized Ramsey--Tur\'an function $\mathrm{RT}(n,K_s,K_t,o(n))$, which is the maximum possible number of copies of $K_s$ in an $n$-vertex $K_t$-free graph with independence number $o(n)$. The case when $s=2$ was settled by…

Combinatorics · Mathematics 2024-03-20 Jun Gao , Suyun Jiang , Hong Liu , Maya Sankar

Ramsey-Tur\'{a}n type problems were initiated by Erd\H{o}s and S\'{o}s in 1969. Given integers $p, q\ge2$, a graph $G$ is $(K_p,K_q)$-free if there exists a red/blue edge coloring of $G$ such that it contains neither a red $K_p$ nor a blue…

Combinatorics · Mathematics 2026-04-28 Xinyu Hu , Qizhong Lin

Given two graphs $G$ and $H$ with $H\subseteq G$ we consider the anti-Ramsey function $AR(G,H)$ which is the maximum number of colors in any edge-coloring of $G$ so that every copy of $H$ receives the same color on at least one pair of…

Combinatorics · Mathematics 2015-11-19 Elliot Krop , Michelle York

Given a graph $H$, the maximal anti-Ramsey function $f(n,e,H)$ denotes the minimum integer $f$ for which there exists an $n$-vertex graph $G$ with at least $e$ edges admitting an edge-coloring with $f$ colors in which each copy of $H$ in…

Combinatorics · Mathematics 2026-03-20 Matija Bucic , Kaizhe Chen , Jie Ma

For two graphs $G$ and $H$, let $r(G,H)$ and $r_*(G,H)$ denote the Ramsey number and star-critical Ramsey number of $G$ versus $H$, respectively. In 1996, Li and Rousseau proved that $r(K_{m},F_{t,n})=tn(m-1)+1$ for $m\geq 3$ and…

Combinatorics · Mathematics 2021-11-12 Maoqun Wang , Jianguo Qian

Let $\cal H$ be a family of graphs. The Tur\'an number ${\rm ex}(n,{\cal H})$ is the maximum possible number of edges in an $n$-vertex graph which does not contain any member of $\cal H$ as a subgraph. As a common generalization of…

Combinatorics · Mathematics 2024-12-13 Chunyang Dou , Bo Ning , Xing Peng

Ore in 1961 determined the maximum number of edges in graphs not containing a Hamiltonian cycle, and Tur\'{a}n in 1941 found the maximum number of edges in graphs not containing a $K_{r+1}$. Motivated by the work of Adamus in 2009 and…

Combinatorics · Mathematics 2025-07-08 Aleyah Dawkins , Rachel Kirsch

Given integers $p, q\ge2$, we say that a graph $G$ is $(K_p,K_q)$-free if there exists a red/blue edge coloring of $G$ such that it contains neither a red $K_p$ nor a blue $K_q$. Fix a function $f( n )$, the Ramsey-Tur\'{a}n number $RT(…

Combinatorics · Mathematics 2023-06-16 Xinyu Hu , Qizhong Lin

The spectral Tur\'an theorem states that the $k$-partite Tur\'an graph is the unique graph attaining the maximum adjacency spectral radius among all graphs of order $n$ containing no the complete graph $K_{k+1}$ as a subgraph. This result…

Combinatorics · Mathematics 2024-08-07 Lele Liu , Zhenyu Ni , Jing Wang , Liying Kang

As a variant of the famous Tur\'an problem, we study $\mathrm{rex}(n,F)$, the maximum number of edges that an $n$-vertex regular graph can have without containing a copy of $F$. We determine $\mathrm{rex}(n,K_{r+1})$ for all pairs of…

Combinatorics · Mathematics 2019-12-24 Dániel Gerbner , Balázs Patkós , Zsolt Tuza , Máté Vizer

The Tur\'an number of a graph $H$, denoted by $ex(n, H)$, is the maximum number of edges in any graph on $n$ vertices containing no $H$ as a subgraph. Let $P_k$ denote the path on $k$ vertices, $S_k$ denote the star on $k+1$ vertices and…

Combinatorics · Mathematics 2022-10-26 Tao Fang , Xiying Yuan

Let $mH$ be the graph formed by $m$ vertex-disjoint copies of a graph $H$. Let $G \to (H)_r$ denote that, in any $r$-colouring of the edges of $G$, there exists a monochromatic copy of $H$. In 1975, Burr, Erd\H{o}s, and Spencer showed that…

Combinatorics · Mathematics 2026-05-21 Lucas Aragão , Xinbu Cheng , Rafael Filipe , Rafael Miyazaki , Danni Peng , Zhifei Yan

Let $F$ be a graph. A hypergraph is called Berge-$F$ if it can be obtained by replacing each edge of $F$ by a hyperedge containing it. Let $\mathcal{F}$ be a family of graphs. The Tur\'an number of Berge-$\mathcal{F}$ is the maximum…

Combinatorics · Mathematics 2018-07-26 Dániel Gerbner , Abhishek Methuku , Máté Vizer
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