2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/172130We show that there is a metric on the Gromoll-Meyer sphere with positive sectional curvature.A referee discovered an error in the statement of Theorem 5.3. This error is corrected and the result is renamed, Lemma 5.3. A coarse outline has been added at the end of the introduction. 95 pagesDifferential Geometry53Cxxtext