2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/141764In this paper we present a proof of a Neumann type maximum principle for the Laplace operator on compact Riemannian manifolds. A key p oint is the simple geometric nature of the constant in the a priori estimate of this maximum principle. In particular, this maximum principle can be applied to manifolds with Ricci curvature bounded from below and diameter bounded from above to yield a maximum estimate without dependence on a positive lower bound for the volume.In Theorem A, the previous maximum estimate in terms of the isoperimetric constant is replaced by a maximum estimate in terms of the volume-normalized isoperimetric constant. The statements of Gallot's estimate for the isoperimetric constant are correctedDifferential Geometry53CXXtext