2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/119109Let M be a Poincare duality space of dimension at least four. In this paper we describe a complete obstruction to realizing the diagonal map M -> M x M by a Poincare embedding. The obstruction group depends only on the fundamental group and the parity of the dimension of M.Fixed some references, minor typos and improved some formulationsAlgebraic Topology57P10; 55P91text