Homotopy type of manifolds with partially horoconvex boundary

Abstract

Let $M$ be an $n$-dimensional compact connected manifold with boundary, $κ>0$ a constant and $1\leq q\leq n-1$ an integer. We prove that $M$ supports a Riemannian metric with the interior $q$-curvature $K_q\geq -qκ^2$ and the boundary $q$-curvature $Λ_q\geq qκ$, if and only if $M$ has the homotopy type of a CW complex with a finite number of cells with dimension $\leq (q-1)$. Moreover, any Riemannian manifold $M$ with sectional curvature $K\geq -κ^2$ and boundary principal curvature $Λ\geq κ$ is diffeomorphic to the standard closed $n$-ball.