# Tag Archives: ramsey theory

## Hales-Jewett and a generalized van der Warden Theorems

The Hales-Jewett theorem is one of the most fundamental results in Ramsey theory, implying the celebrated van der Waerden theorem on arithmetic progressions, as well an its multidimensional and IP versions. One interesting property of the Hales-Jewett’s theorem is that … Continue reading

## Ramsey, Hindman and Milliken-Taylor Theorems

Ramsey’s theorem is probably the most famous result of Ramsey theory, giving it its name. Essentially it states that a finite coloring of a certain structure contains a monochromatic copy of the original structure, in this case the structure being … Continue reading

## Brauer’s theorem and a coloring trick of Bergelson

— 1. Introduction — Ramsey theory concerns essentially two types of results: coloring and density results. Coloring results state that given a finite partition of some structured set (usually ) one of the cells in the partition still has some … Continue reading

Posted in Combinatorics, Ergodic Theory, Ramsey Theory, Tool | | 3 Comments

## Hales-Jewett Theorem

— 1. Introduction — One of the earliest posts I wrote on this blog contained a proof of the van der Waerden’s Theorem on arithmetic progressions. That proof was topological in nature and illustrated the interesting relation between some problems … Continue reading

Posted in Combinatorics, Ramsey Theory | | 6 Comments

## Properties of ultrafilters and a Theorem on arithmetic combinatorics

A Theorem of Schur (one of the earliest results in Ramsey Theory) asserts that given any finite coloring of the set of natural numbers , there exist of the same color such that also has the same color. As a … Continue reading

Posted in Combinatorics, Ramsey Theory | | 13 Comments

## Convergence along ultrafilters – part II

This is the second of a series of two post whose aim is to prove the following recurrence theorem. Recall that a measure preserving system (shortened to m.p.s.) is a quadruple , where is a probability space and preserves the … Continue reading

Posted in Combinatorics, Ergodic Theory, Ramsey Theory | | 1 Comment

## Convergence along ultrafilters

— 1. Introduction — On my previous post about recurrent theorems I stated Khintchine’s theorem and Sarkozy’s theorem. There I classified Khintchine’s theorem as a theorem about large intersections and Sarkozy’s theorem as a theorem about large recurrent times. This … Continue reading

Posted in Ergodic Theory, Ramsey Theory, Tool | | 8 Comments