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We present a new, category theoretic point of view on finite Ramsey theory. Our aims are as follows: -- to define the category theoretic notions needed for the development of finite Ramsey Theory, -- to state, in terms of these notions, the…

Combinatorics · Mathematics 2022-05-24 Sławomir Solecki

We prove that for any choice of parameters $k,t,\lambda$ the class of all finite ordered designs with parameters $k,t,\lambda$ is a Ramsey class.

Combinatorics · Mathematics 2017-05-09 Jan Hubička , Jaroslav Nešetřil

We prove that double exponentiation is an upper bound to Ramsey theorem for colouring of pairs when we want to predetermine the order of the differences of successive members of the homogeneous set.

Combinatorics · Mathematics 2016-09-06 Saharon Shelah

We prove the Ramsey property for classes of ordered structures with closures and given local properties. This generalises earlier results: the Ne\v{s}et\v{r}il-R\"odl Theorem, the Ramsey property of partial orders and metric spaces as well…

Combinatorics · Mathematics 2019-09-04 Jan Hubička , Jaroslav Nešetřil

We further develop the theory of layered semigroups, as introduced by Farah, Hindman and McLeod, providing a general framework to prove Ramsey statements about such a semigroup $S$. By nonstandard and topological arguments, we show Ramsey…

Combinatorics · Mathematics 2021-04-26 Jordan Mitchell Barrett

We state the Ramsey property of classes of ordered structures with closures and given local properties. This generalises many old and new results: the Ne\v{s}et\v{r}il-R\"{o}dl Theorem, the author's Ramsey lift of bowtie-free graphs as well…

Combinatorics · Mathematics 2017-06-07 Jan Hubička , Jaroslav Nešetřil

Ramsey theory is the study of conditions under which mathematical objects show order when partitioned. Ramsey theory on the integers concerns itself with partitions of $[1,n]$ into $r$ subsets and asks the question whether one (or more) of…

Combinatorics · Mathematics 2014-04-30 Mano Vikash Janardhanan

Raimi's theorem guarantees the existence of a partition of $\mathbb{N}$ into two parts with an unavoidable intersection property: for any finite coloring of $\mathbb{N}$, some color class intersects both parts infinitely many times, after…

Combinatorics · Mathematics 2026-01-01 Norbert Hegyvari , Janos Pach , Thang Pham

We introduce a partial order structure on the set of interval orders of a given size, and prove that such a structure is in fact a lattice. We also provide a way to compute meet and join inside this lattice. Finally, we show that, if we…

Combinatorics · Mathematics 2012-03-28 Filippo Disanto , Luca Ferrari , Simone Rinaldi

I prove forcing preservation theorems for products of definable partial orders preserving the cofinality of the meager or null ideal. Rectangular Ramsey theorems for related ideals follow from the proofs.

Logic · Mathematics 2007-05-23 Jindrich Zapletal

We show that Ramsey theory, a domain presently conceived to guarantee the existence of large homogeneous sets for partitions on k-tuples of words (for every natural number k) over a finite alphabet, can be extended to one for partitions on…

Combinatorics · Mathematics 2007-05-23 V. Farmaki , S. Negrepontis

For a partial order $\preceq$ on a set X and an equivalency relation S defined on the same set X we derive a necessary and sufficient condition for the existence of such a total preorder on X whose asymmetric part contains the asymmetric…

Functional Analysis · Mathematics 2011-11-08 Dmitry V. Akopian , Valentin V. Gorokhovik

Let $\mathbf{k}$ denote the totally ordered set (or chain) on $k$ elements. The product $\mathbf{k}^t=\mathbf{k}\times\cdots\times\mathbf{k}$ is a poset called a grid. This paper discusses several loosely related results on the Ramsey…

Combinatorics · Mathematics 2022-06-30 Csaba Biró , Sida Wan

Ramsey theory for words over a finite alphabet was unified in the work of Carlson and Furstenberg-Katznelson. Carlson, in the same work, outlined a method to extend the theory for words over an infinite alphabet, but subject to a fixed…

Combinatorics · Mathematics 2010-11-03 Vassiliki Farmaki , Andreas Koutsogiannis

Ramsey's theorem states that each coloring has an infinite homogeneous set, but these sets can be arbitrarily spread out. Paul Erdos and Fred Galvin proved that for each coloring f, there is an infinite set that is "packed together" which…

Logic · Mathematics 2013-02-12 Stephen Flood

We study the number of linear extensions of a partial order with a given proportion of comparable pairs of elements, and estimate the maximum and minimum possible numbers. We also consider a random interval partial order on $n$ elements,…

Combinatorics · Mathematics 2018-10-16 Colin McDiarmid , David Penman , Vasileios Iliopoulos

Classical Ramsey theory has successfully extended to relational structures, yielding a wealth of results that have profoundly influenced other areas of mathematics. Interestingly, the same development has not occurred in the case of dual…

Combinatorics · Mathematics 2025-07-02 Aleksa Džuklevski , Dragan Mašulović

In this paper, we study the well extension of strict(irreflective) partial well orderings. We first prove that any partially well-ordered structure <A, R> can be extended to a well-ordered one. Then we prove that every linear extension of…

Logic in Computer Science · Computer Science 2015-07-28 Haoxiang Lin

We find all linear orders $L,L_2$ such that $L\to(\mathbb Z,L_2)^2$. The key is the identification of the orders $L$ such that $L\to(\mathbb Z,\mathbb Z)^1$.

Logic · Mathematics 2025-03-20 Andrés Eduardo Caicedo

I will give a presentation of an abstract approach to finite Ramsey theory found in an earlier paper of mine. I will prove from it a common generalization of Deuber's Ramsey theorem for regular trees and a recent Ramsey theorem of Jasinski…

Combinatorics · Mathematics 2012-10-03 Slawomir Solecki