mathlib

ad5afc21 - feat(combinatorics/hales_jewett): Hales-Jewett and Van der Waerden (#8019)

feat(combinatorics/hales_jewett): Hales-Jewett and Van der Waerden (#8019) Proves the Hales-Jewett theorem (a fundamental result in Ramsey theory on combinatorial lines) and deduces (a generalised version of) Van der Waerden's theorem on arithmetic progressions. Co-authored-by: YaelDillies <yael.dillies@gmail.com>