Results 21 to 30 of about 51 (51)

Block sizes in the block sets conjecture

open access: yesForum of Mathematics, Sigma
A set X is called Euclidean Ramsey if, for any k and sufficiently large n, every k-colouring of $\mathbb {R}^n$ contains a monochromatic congruent copy of X.
Maria-Romina Ivan   +2 more
doaj   +1 more source

On the Vertex Folkman Numbers Fv(2,...,2;q) [PDF]

open access: yes, 2009
2000 Mathematics Subject Classification: 05C55.In this paper we shall compute the Folkman numbers ...
Nenov, Nedyalko
core  

Bohr Topologies and Partition Theorems for Vector Spaces

open access: yes, 1997
We prove a Ramsey-style theorem for sequences of vectors in an infinite-dimensional vector space over a finite field. As an application of this theorem, we prove that there are countably infinite Abelian groups whose Bohr topologies are not homeomorphic.
Kenneth Kunen, Kunen, Kenneth
core   +1 more source

New Upper Bound for the Edge Folkman Number Fe(3,5;13) [PDF]

open access: yes, 2008
2000 Mathematics Subject Classification: 05C55.For a given graph G let V(G) and E(G) denote the vertex and the edge set of G respevtively. The symbol G e → (a1, …, ar) means that in every r-coloring of E(G) there exists a monochromatic ai-clique of ...
Kolev, Nikolay
core  

The power of many colours

open access: yesForum of Mathematics, Sigma
A classical problem, due to Gerencsér and Gyárfás from 1967, asks how large a monochromatic connected component can we guarantee in any r-edge colouring of $K_n$ ?
Noga Alon   +3 more
doaj   +1 more source

Variations of classical selection principles: an overview

open access: yes, 2020
The paper is an overview of selected results on weaker forms of classical selection principles of Menger, Hurewicz, Rothberger and Gerlits-Nagy obtained in the last few years.
Kočinac, Ljubiša D.R.
core  

Topological methods in zero-sum Ramsey theory

open access: yesForum of Mathematics, Sigma
A landmark result of Erdős, Ginzburg, and Ziv (EGZ) states that any sequence of $2n-1$ elements in ${\mathbb {Z}}/n$ contains a zero-sum subsequence of length n.
Florian Frick   +7 more
doaj   +1 more source

The weak Ramsey property and extreme amenability

open access: yesForum of Mathematics, Sigma
We extend the Kechris–Pestov–Todorčević correspondence to weak Fraïssé categories and automorphism groups of generic objects. The new ingredient is the weak Ramsey property.
Adam Bartoš   +3 more
doaj   +1 more source

Echeloned Spaces

open access: yesForum of Mathematics, Sigma
We introduce the notion of echeloned spaces – an order-theoretic abstraction of metric spaces. The first step is to characterize metrizable echeloned spaces. It turns out that morphisms between metrizable echeloned spaces are uniformly continuous or have
Maxime Gheysens   +4 more
doaj   +1 more source

Ramsey-Type Results for Oriented Trees

open access: yes, 2007
. For a graph G and a digraph ~ H, we write G! ~ H (respectively, G a ! ~ H) if every orientation (respectively, acyclic orientation) of the edges of G results in an induced copy of ~ H. In this note we study how small the graphs G such that G!
Vojtech Rödl   +2 more
core  

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