1st eigenvalue pinching for convex hypersurfaces in a Riemannian manifold
arXiv:1905.05572
Abstract
Let be a closed convex hypersurface lying in a convex ball of the ambient -manifold . We prove that, by pinching Heintze-Reilly's inequality via sectional curvature upper bound of , 1st eigenvalue and mean curvature of , not only is Hausdorff close and almost isometric to a geodesic sphere in , but also its enclosed domain is -close to a geodesic ball of constant curvature.
6 pages