2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/69404We prove that a riemannian metric on the 2-sphere or the projective plane can be C2-approximated by a smooth metric whose geodesic flow has an elliptic closed geodesic.Differential GeometryDynamical Systems53D25, 37D40, 37D30text