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We estimate the $3$-colour bipartite Ramsey number for balanced bipartite graphs $H$ with small bandwidth and bounded maximum degree. More precisely, we show that the minimum value of $N$ such that in any $3$-edge colouring of $K_{N,N}$…

Combinatorics · Mathematics 2018-04-10 Guilherme Oliveira Mota

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

Gallai-colorings are edge-colored complete graphs in which there are no rainbow triangles. Within such colored complete graphs, we consider Ramsey-type questions, looking for specified monochromatic graphs. In this work, we consider…

Combinatorics · Mathematics 2017-10-31 Haibo Wu , Colton Magnant , Pouria Salehi Nowbandegani , Suman Xia

For the given bipartite graphs $G_1,G_2,\ldots,G_t$, the multicolor bipartite Ramsey number $BR(G_1,G_2,\ldots,G_t)$ is the smallest positive integer $b$ such that any $t$-edge-coloring of $K_{b,b}$ contains a monochromatic subgraph…

Combinatorics · Mathematics 2024-02-28 Mostafa Gholami , Yaser Rowshan

We investigate size Ramsey numbers involving bipartite graphs. It is proved that, if each forbidden graph is fixed or grows with n (in a certain uniform manner), then the extremal function has a linear asymptotics. The corresponding slope…

Combinatorics · Mathematics 2007-05-23 Oleg Pikhurko

The $k$-colour bipartite Ramsey number of a bipartite graph $H$ is the least integer $n$ for which every $k$-edge-coloured complete bipartite graph $K_{n,n}$ contains a monochromatic copy of $H$. The study of bipartite Ramsey numbers was…

Combinatorics · Mathematics 2019-08-07 Matija Bucić , Shoham Letzter , Benny Sudakov

In this paper we study Ramsey numbers for trees of diameter 3 (bistars) vs., respectively, trees of diameter 2 (stars), complete graphs, and many complete graphs. In the case of bistars vs. many complete graphs, we determine this number…

Combinatorics · Mathematics 2014-04-08 Jeremy F. Alm , Nicholas Hommowun , Aaron Schneider

Given bipartite graphs $G_1, \ldots, G_n$, the bipartite Ramsey number $BR(G_1,\ldots, G_n)$ is the last integer $b$ such that any complete bipartite graph $K_{b,b}$ with edges coloured with colours $1,2,\ldots,n$ contains a copy of some…

Combinatorics · Mathematics 2022-03-01 Yaser Rowshan

Let $H\xrightarrow{s} G$ denote that any edge-coloring of $H$ by $s$ colors contains a monochromatic $G$. The degree Ramsey number $r_{\Delta}(G;s)$ is defined to be $\min\{\Delta(H):H\xrightarrow{s} G\}$, and the degree bipartite Ramsey…

Combinatorics · Mathematics 2019-09-04 Ye Wang , Yusheng Li , Yan Li

In a recent work on the bipartite Erd\H{o}s-R\'{e}nyi graph, Do et al. (2023) established upper bounds on the number of connected labeled bipartite graphs with a fixed surplus. We use some recent encodings of bipartite random graphs in…

Combinatorics · Mathematics 2024-11-15 David Clancy

The $k$-colour bipartite Ramsey number of a bipartite graph $H$ is the least integer $N$ for which every $k$-edge-coloured complete bipartite graph $K_{N,N}$ contains a monochromatic copy of $H$. The study of bipartite Ramsey numbers was…

Combinatorics · Mathematics 2019-09-18 Matija Bucic , Shoham Letzter , Benny Sudakov

The size-Ramsey number of a graph $G$ is the minimum number of edges in a graph $H$ such that every 2-edge-coloring of $H$ yields a monochromatic copy of $G$. Size-Ramsey numbers of graphs have been studied for almost 40 years with…

Combinatorics · Mathematics 2015-03-24 Andrzej Dudek , Steven La Fleur , Dhruv Mubayi , Vojtech Rodl

An ordered graph $G$ is a graph together with a specified linear ordering on the vertices, and its interval chromatic number is the minimum number of independent sets consisting of consecutive vertices that are needed to partition the…

Combinatorics · Mathematics 2021-02-18 Dana Neidinger , Douglas B. West

For given graphs $G_{1}, G_{2}, ... , G_{k}, k \geq 2$, the multicolor Ramsey number $R(G_{1}, G_{2}, ... , G_{k})$ is the smallest integer $n$ such that if we arbitrarily color the edges of the complete graph of order $n$ with $k$ colors,…

Combinatorics · Mathematics 2017-07-24 Farideh Khoeini , Tomasz Dzido

In a $(G^1,G^2)$ coloring of a graph $G$, every edge of $G$ is in $G^1$ or $G^2$. For two bipartite graphs $H_1$ and $H_2$, the bipartite Ramsey number $BR(H_1, H_2)$ is the least integer $b\geq 1$, such that for every $(G^1, G^2)$ coloring…

Combinatorics · Mathematics 2022-02-11 Yaser Rowshan

For bipartite graphs $G$ and $H$ and a positive integer $m$, the $m$-bipartite Ramsey number $BR_m(G, H)$ of $G$ and $H$ is the smallest integer $n$, such that every red-blue coloring of $K_{m,n}$ results in a red $G$ or a blue $H$.…

Combinatorics · Mathematics 2022-02-01 Yaser Rowshan , Mostafa Gholami

A graph $G$ is Ramsey for a graph $H$ if every 2-colouring of the edges of $G$ contains a monochromatic copy of $H$. We consider the following question: if $H$ has bounded treewidth, is there a `sparse' graph $G$ that is Ramsey for $H$? Two…

Combinatorics · Mathematics 2019-07-30 Nina Kamcev , Anita Liebenau , David R. Wood , Liana Yepremyan

We give an exponential improvement to the lower bound on diagonal Ramsey numbers for any fixed number of colors greater than two.

Combinatorics · Mathematics 2020-11-30 David Conlon , Asaf Ferber

Given bipartite graphs $H_1$, \dots , $H_k$, the bipartite Ramsey number $br(H_1,\dots, H_k)$ is the minimum integer $N$ such that any $k$-edge-coloring of complete bipartite graph $K_{N, N}$ contains a monochromatic $H_i$ in color $i$ for…

Combinatorics · Mathematics 2023-01-31 Zilong Yan , Yuejian Peng

In this paper, we present several density-type theorems which show how to find a copy of a sparse bipartite graph in a graph of positive density. Our results imply several new bounds for classical problems in graph Ramsey theory and improve…

Combinatorics · Mathematics 2007-11-12 Jacob Fox , Benny Sudakov
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