2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/65136We prove that for each closed smooth spin 4-manifold M there exists a closed smooth 4-manifold N such that the connected sum M # N admits a conformally flat Riemannian metric.9 pages, 2 figuresDifferential GeometryGeometric Topology53C15, 57M50text