2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/142441Gromoll and Meyer have represented a certain exotic 7-sphere $Σ^7$ as a biquotient of the Lie group $G = Sp(2)$. We show for a 2-parameter family of left invariant metrics on $G$ that the induced metric on $Σ^7$ has strictly positive sectional curvature at all points outside four subvarieties of codimension $\geq 1$ which we describe explicitly.8 pages, 1 figure, to appear in Proc. Amer. Math. SocDifferential Geometry53C20; 53C30text