A refinement of G\"unther's candle inequality

Abstract

We analyze an upper bound on the curvature of a Riemannian manifold, using "root-Ricci" curvature, which is in between a sectional curvature bound and a Ricci curvature bound. (A special case of root-Ricci curvature was previously discovered by Osserman and Sarnak for a different but related purpose.) We prove that our root-Ricci bound implies G\"unther's inequality on the candle function of a manifold, thus bringing that inequality closer in form to the complementary inequality due to Bishop.