2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/137123These are introductory notes on some aspects of concentration of measure in the presence of an acting group and its links to Ramsey theory.29 pages, 6 figures, TeX with l'Enseign. Math. macros, the final version as appears in l'Enseignement MathématiqueFunctional Analysis22F05; 37B05; 60B05; 05D10text