2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/226237This paper gives an overview of Fred Cohen's work and is a summary of the talk which I gave during his 60th birthday conference, held at the University of Tokyo in July 2005.This is the version published by Geometry & Topology Monographs on 7 April 2009Algebraic Topology55P99, 55R80, 20F05, 20F36, 55P42text