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If we two-colour a circle, we can always find an inscribed triangle with angles $(\frac{\pi}{7},\frac{2\pi}{7},\frac{4\pi}{7})$ whose three vertices have the same colour. In fact, Bialostocki and Nielsen showed that it is enough to consider…

Combinatorics · Mathematics 2025-04-29 Gábor Damásdi , Nóra Frankl , János Pach , Dömötör Pálvölgyi

We prove a sharp structural result concerning finite colorings of pairs in well-founded trees.

Combinatorics · Mathematics 2019-05-17 R. M. Causey , C. Doebele

We prove that for any $\ell_p$-norm in the plane with $1<p<\infty$ and for every infinite $\mathcal{M} \subset \mathbb{R}^2$, there exists a two-colouring of the plane such that no isometric copy of $\mathcal{M}$ is monochromatic. On the…

Combinatorics · Mathematics 2025-09-29 Nóra Frankl , Panna Gehér , Arsenii Sagdeev , Géza Tóth

Let $k,l,m$ be integers and $r(k,l,m)$ be the minimum integer $N$ such that for any red-blue-green coloring of $K_{N,N}$, there is a red matching of size at least $k$ in a component, or a blue matching of at least size $l$ in a component,…

Combinatorics · Mathematics 2018-09-19 Zhidan Luo , Yuejian Peng

There are many extremely challenging problems about existence of monochromatic arithmetic progressions in colorings of groups. Many theorems hold only for abelian groups as results on non-abelian groups are often much more difficult to…

Combinatorics · Mathematics 2014-11-11 Erik Sjöland

In this article, we study a degenerate version of Ramsey's theorem for pairs and two colors ($\mathsf{RT}^2_2$), in which the homogeneous sets for color 1 are of bounded size. By $\mathsf{RT}^2_2$, it follows that every such coloring admits…

Logic · Mathematics 2025-09-05 Quentin Le Houérou , Ludovic Patey

A system of linear equations with integer coefficients is partition regular over a subset S of the reals if, whenever S\{0} is finitely coloured, there is a solution to the system contained in one colour class. It has been known for some…

Combinatorics · Mathematics 2018-09-05 Ben Barber , Neil Hindman , Imre Leader , Dona Strauss

We both survey and extend a new technique from Lu Liu to prove separation theorems between products of Ramsey-type theorems over computable reducibility. We use this technique to show that Ramsey's theorem for $n$-tuples and three colors is…

Logic · Mathematics 2024-07-03 Julien Cervelle , William Gaudelier , Ludovic Levy Patey

Schur's Theorem states that, for any $r \in \mathbb{Z}^+$, there exists a minimum integer $S(r)$ such that every $r$-coloring of $\{1,2,\dots,S(r)\}$ admits a monochromatic solution to $x+y=z$. Recently, Budden determined the related…

Combinatorics · Mathematics 2025-03-03 Yaping Mao , Aaron Robertson , Jian Wang , Chenxu Yang , Gang Yang

Motivated by a problem in additive Ramsey theory, we extend Todorcevic's partitions of three-dimensional combinatorial cubes to handle additional three-dimensional objects. As a corollary, we get that if the continuum hypothesis fails, then…

Logic · Mathematics 2023-01-05 Ido Feldman , Assaf Rinot

We prove that for any partition of the plane into a closed set $C$ and an open set $O$ and for any configuration $T$ of three points, there is a translated and rotated copy of $T$ contained in $C$ or in $O$. Apart from that, we consider…

Combinatorics · Mathematics 2011-04-29 Vit Jelinek , Jan Kyncl , Rudolf Stolar , Tomas Valla

We use the combinatorial properties of central sets to prove a result about the existence of exponential monochromatic patterns, in the style of Hindman's Finite Sums Theorem. More precisely, we prove that for every finite coloring of the…

Combinatorics · Mathematics 2022-11-30 Mauro Di Nasso , Mariaclara Ragosta

In a recent paper, Thejitha and Fathima introduced the overcolored partition function $\bar{a}_{r,s}(n)$, which enumerates overpartitions in which even parts may appear in one of $r$ colors and odd parts in one of $s$ colors, for fixed…

Number Theory · Mathematics 2026-03-16 Imdadul Hussain , Suparno Ghoshal , Arijit Jana

We give a short, explicit proof of Hindman's Theorem that in every finite coloring of the integers, there is an infinite set all of whose finite sums have the same color. We give several exampls of colorings of the integers which do not…

Combinatorics · Mathematics 2011-07-05 Henry Towsner

Some of the classical results of Ramsey Theory can be naturally stated in terms of image partition regularity of matrices. There have been many significant results of image partition regular matrices as well as image partition regular…

Combinatorics · Mathematics 2014-09-23 Tanushree Biswas

The chromatic functor of a simple graph is a functorization of the chromatic polynomial. M. Yoshinaga showed in \cite{Yoshinaga2015} that two finite graphs have isomorphic chromatic functors if and only if they have the same chromatic…

Combinatorics · Mathematics 2019-08-15 Ye Liu

We get a quite maximal version of the colouring property $Pr_1$ by proving $Pr_1(\lambda,\lambda,\lambda,\theta)$ when $\lambda = \partial^+, \partial > \theta$ are regular cardinals.

Logic · Mathematics 2021-05-14 Saharon Shelah

It is proved that for each natural number $n$, if $\left| \mathbb{R} \right| = {\aleph}_{n}$, then there is a coloring of ${\left[ \mathbb{R} \right]}^{n+2}$ into ${\aleph}_{0}$ colors that takes all colors on ${\left[ X \right]}^{n+2}$…

Logic · Mathematics 2022-04-06 Dilip Raghavan , Stevo Todorcevic

Given a fixed integer $n$, we prove Ramsey-type theorems for the classes of all finite ordered $n$-colorable graphs, finite $n$-colorable graphs, finite ordered $n$-chromatic graphs, and finite $n$-chromatic graphs.

Combinatorics · Mathematics 2014-01-07 L. Nguyen Van Thé

Hindman's Theorem says that every finite coloring of the positive natural numbers has a monochromatic set of finite sums. Ramsey algebras, recently introduced, are structures that satisfy an analogue of Hindman's Theorem. It is an open…

Logic · Mathematics 2016-08-04 Wen Chean Teh