2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/99976This paper expands some of the issues of the paper math.SG/0506449. We introduce a new technique to produce symplectic manifolds, by taking a symplectic non-free action of a finite group on a symplectic manifold and resolving symplectically the singularities of the quotient. We also introduce a new type of Massey product to detect non-formality. This allows to show the first example of a non-formal simply connected compact symplectic manifold of dimension 8.21 pages, no figures; v2. exposition greatly improvedSymplectic GeometryAlgebraic Topology57R17; 55S30; 55P62text