The Minding formula and its applications

Abstract

We apply the Minding Formula for geodesic curvature and the Gauss-Bonnet Formula to calculate the total Gaussian curvature of certain 2-dimensional open complete branched Riemannian manifolds, the \(\cal M\) surfaces. We prove that for an \(\cal M\) surface, the total curvature depends only on its Euler characteristic and the local behaviour of its metric at ends and branch points. Then we check that many important surfaces, such as complete minimal surfaces in \({\Bbb R}^n\) with finite total curvature, complete constant mean curvature surfaces in hyperbolic 3-space H 3 (–1) with finite total curvature, are actually branch point free \(\cal M\) surfaces. Therefore as corollaries we give simple proofs of some classical theorems such as the Chern-Osserman theorem for complete minimal surfaces in \({\Bbb R}^n\) with finite total curvature. For the reader's convenience, we also derive the Minding Formula.