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The induced Ramsey number $r_{\mathrm{ind}}(G,H)$ is defined as the minimum order of a graph $F$ on such that any 2-coloring of its edges with red and blue leads to either a red induced copy of $G$ or a blue induced copy of $H$. Motivated…

Combinatorics · Mathematics 2026-03-23 Chuang Zhong , Masaki Kashima , Yaping Mao , Yan Zhao

We study the generalized Ramsey numbers $f(Q_n, C_{k}, q)$, that is, the minimum number of colors needed to edge-color the hypercube $Q_n$ so that every copy of the cycle $C_{k}$ has at least $q$ colors. Our main result is that for any…

Combinatorics · Mathematics 2026-01-23 Emily Heath , Coy Schwieder , Shira Zerbib

A $k$-dimensional box is the cartesian product $R_1 \times R_2 \times ... \times R_k$ where each $R_i$ is a closed interval on the real line. The {\it boxicity} of a graph $G$, denoted as $box(G)$, is the minimum integer $k$ such that $G$…

Combinatorics · Mathematics 2007-12-18 L. Sunil Chandran , Anita Das , Chintan Shah

Given two graphs $G$ and $H$, the {Ramsey number} $R(G,H)$ is the smallest positive integer $N$ such that every 2-coloring of the edges of $K_{N}$ contains either a red $G$ or a blue $H$. Let $K_{N-1}\sqcup K_{1,k}$ be the graph obtained…

Combinatorics · Mathematics 2023-08-22 Taiping Jiang , Xinmin Hou

Bipartite Ramsey numbers is the smallest size of a complete bipartite graph $K_{N,N}$ such that every edge-coloring with a given number of colors inevitably yields a monochromatic copy of a prescribed bipartite graph. While exact values…

Combinatorics · Mathematics 2026-04-29 Meng Ji

An ordered graph is a simple graph with an ordering on its vertices. Define the ordered path $P_n$ to be the monotone increasing path with $n$ edges. The ordered size Ramsey number $\tilde{r}(P_r,P_s)$ is the minimum number $m$ for which…

Combinatorics · Mathematics 2019-05-21 József Balogh , Felix Christian Clemen , Emily Heath , Mikhail Lavrov

An ordered graph is a graph whose vertex set is equipped with a total order. The ordered complete graph $K_N^<$ is the complete graph with vertex set $[N]$ equipped with the natural ordering of the integers. Given an ordered graph $H$, the…

Combinatorics · Mathematics 2026-03-24 Gaurav Kucheriya , Allan Lo , Jan Petr , Amedeo Sgueglia , Jun Yan

Let $F_n$ be the graph on $2n+1$ vertices consisting of $n$ triangles meeting at a single vertex. After a number of improvements over the years, it is currently known that the Ramsey number of $F_n$ is between $4.5n-5$ (Chen, Yu, Zhao) and…

Combinatorics · Mathematics 2026-03-31 Louis DeBiasio , Tucker Wimbish

Let $G$ be a graph and $\Gamma$ a finite abelian group. The zero-sum Ramsey number of $G$ over $\Gamma$, denoted by $R(G, \Gamma)$, is the smallest positive integer $t$ (if it exists) such that any edge-colouring $c:E(K_t)\to\Gamma$…

Combinatorics · Mathematics 2026-05-11 Jasmin Katz , Xiaopan Lian , Alexandru Malekshahian , Andrey Shapiro

The classical Ramsey numbers $r(s,t)$ denote the minimum $n$ such that every red-blue coloring of the edges of the complete graph $K_n$ contains either a red clique of order $s$ or a blue clique of order $t$. These quantities are the…

Combinatorics · Mathematics 2025-04-01 Jacques Verstraete

The Ramsey number $R_X(p,q)$ for a class of graphs $X$ is the minimum $n$ such that every graph in $X$ with at least $n$ vertices has either a clique of size $p$ or an independent set of size $q$. We say that Ramsey numbers are linear in…

Combinatorics · Mathematics 2020-12-07 Bogdan Alecu , Aistis Atminas , Vadim Lozin , Viktor Zamaraev

A graph $G$ is $q$-Ramsey for another graph $H$ if in any $q$-edge-colouring of $G$ there is a monochromatic copy of $H$, and the classic Ramsey problem asks for the minimum number of vertices in such a graph. This was broadened in the…

Combinatorics · Mathematics 2025-03-05 Simona Boyadzhiyska , Dennis Clemens , Shagnik Das , Pranshu Gupta

We prove that $s_r(K_k) = O(k^5 r^{5/2})$, where $s_r(K_k)$ is the Ramsey parameter introduced by Burr, Erd\H{o}s and Lov\'{a}sz in 1976, which is defined as the smallest minimum degree of a graph $G$ such that any $r$-colouring of the…

Combinatorics · Mathematics 2022-10-25 John Bamberg , Anurag Bishnoi , Thomas Lesgourgues

Operator systems of matrices can be viewed as quantum analogues of finite graphs. This analogy suggests many natural combinatorial questions in linear algebra. We determine the quantum Ramsey numbers $QR(2,k)$ and the lower quantum Tur\'an…

Operator Algebras · Mathematics 2025-07-09 Andrew Allen , Andre Kornell

The $r$-size-Ramsey number $\hat{R}_r(H)$ of a graph $H$ is the smallest number of edges a graph $G$ can have, such that for every edge-coloring of $G$ with $r$ colors there exists a monochromatic copy of $H$ in $G$. For a graph $H$, we…

Combinatorics · Mathematics 2020-11-12 Nemanja Draganić , Michael Krivelevich , Rajko Nenadov

We consider the following problem posed by Erdos in 1962. Suppose that $G$ is an $n$-vertex graph where the number of $s$-cliques in $G$ is $t$. How small can the independence number of $G$ be? Our main result suggests that for fixed $s$,…

Combinatorics · Mathematics 2018-01-12 Tom Bohman , Dhruv Mubayi

The Ramsey number $r(t;\ell)$ is the smallest $n$ such that every $\ell$-coloring of the edges of $K_n$ gives a monochromatic $K_{t}$. In recent years, there have been several improvements on asymptotic lower bounds for these numbers when…

Combinatorics · Mathematics 2026-02-03 Yamaan Attwa , Albert López Vidal , Patrick Morris

A graph G is r-Ramsey for a graph H, denoted by G\rightarrow (H)_r, if every r-colouring of the edges of G contains a monochromatic copy of H. The graph G is called r-Ramsey-minimal for H if it is r-Ramsey for H but no proper subgraph of G…

Combinatorics · Mathematics 2015-02-11 Jacob Fox , Andrey Grinshpun , Anita Liebenau , Yury Person , Tibor Szabo

We introduce and study a variant of Ramsey numbers for edge-ordered graphs, that is, graphs with linearly ordered sets of edges. The edge-ordered Ramsey number $\overline{R}_e(\mathfrak{G})$ of an edge-ordered graph $\mathfrak{G}$ is the…

Combinatorics · Mathematics 2021-04-16 Martin Balko , Máté Vizer

A unit cube in $k$ dimensional space (or \emph{$k$-cube} in short) is defined as the Cartesian product $R_1\times R_2\times...\times R_k$ where $R_i$(for $1\leq i\leq k$) is a closed interval of the form $[a_i,a_i+1]$ on the real line. A…

Discrete Mathematics · Computer Science 2008-03-26 L. Sunil Chandran , Mathew C. Francis , Naveen Sivadasan