2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/67647We prove that for every natural number k there are simply connected topological four-manifolds which have at leat k distinct smooth structures supporting Einstein metrics, and also have infinitely many distinct smooth structures not supporting Einstein metrics. Moreover, all these smooth structures become diffeomorphic after connected sum with only one copy of the complex projective plane. We prove that manifolds with these properties cover a large geographical area.23 pagesGeometric TopologyAlgebraic GeometryDifferential GeometrySymplectic Geometry57R55; 14J29, 14J80, 53C25, 57R57text