This paper introduces an
isometric extension procedure for Riemannian manifolds with boundary, which
preserves some lower curvature bound and produces a totally geodesic boundary. As
immediate applications of this construction, one obtains in particular upper volume
bounds, an upper intrinsic diameter bound for the boundary, precompactness, and a
homeomorphism finiteness theorem for certain classes of manifolds with boundary, as
well as a characterization up to homotopy of Gromov–Hausdorff limits of such a
class.
Keywords
manifold with boundary, extension, Gromov–Hausdorff
topology