# The Nash-Williams Partition Theorem

Lawrence C. Paulson

16 May 2020

### Abstract

In 1965, Nash-Williams discovered a generalisation of the infinite form of Ramsey's theorem. Where the latter concerns infinite sets of n-element sets for some fixed n, the Nash-Williams theorem concerns infinite sets of finite sets (or lists) subject to a “no initial segment” condition. The present formalisation follows a monograph on Ramsey Spaces by Todorčević.