Applications of Ramsey's Theorem

[symplectic_manifold]

Hey, Guys!

I wonder what applications of Ramsey's famous theorem there exist apart from such cases as:
1) constructions of functions in the domain of natural numbers to check some properties of sequences of real numbers.
2) propositions about points in convex postition (Erdos-Szekeres Problem)

I don't ask for detailed descriptions, although they are also welcome.
You can simply give a short sketch of applications in different fields of maths or give a link.

Thanks in advance!

 

[fresh_42]

https://www.combinatorics.org/ojs/index.php/eljc/article/download/DS13/pdf/http://math.uchicago.edu/~may/REUDOCS/Steed.pdf