The topology of complete minimal surfaces of finite total Gaussian curvature

Abstract

RECENTLY GREAT progress has been made in the classical theory of minimal surfaces in R3. For example, the proof of the embedding of the solution to Plateau’s problem for an extremal Jordan curve [lo] and the embedding of a solution to the free boundary value problem [ll], the proof of the bridge theorem [12], the regularity and finiteness of least area oriented surfaces bounding a smooth Jordan curve [5], the uniqueness and topological uniqueness of certain minimal surfaces 18, 9, 121, the proof that a complete stable minimal surface is a plane [l, 31, the existence of a collection of 4 Jordan curves which bound a continuous family of compact minimal surfaces [141, the existence of a complete minimal surface contained between two parallel planes [13] and a theorem [18] which states that if the Gauss map of a complete minimal surface misses 7 points on the ‘sphere, then the minimal surface is a plane. The aim of this work is to begin the exploration of the topological properties of complete minimal surfaces of finite total curvature. First we recall the fundamental classical result of Chern-Osserman [6] that states that such surfaces M are conformally equivalent to compact Riemann surfaces iii punctured in a finite number of points. Furthermore, they prove that the Gauss map on the surface M extends conformally to a. In particular, the theorem of Chern-Osserman implies that such surfaces have finite topological type with a finite number of topological ends and that the normal vectors at infinity on these ends are well defined. (Finite topological type means in this case that M is diffeomorphic to the interior of a compact surface with boundary.) Our first theorem gives a nice description of the topological placement in IX3 of a complete surface of finite topological type which has well defined normal vectors at infinity. We prove that the ends of such surfaces behave like the ends of the catenoid at infinity. More precisely, Theorem 1 shows that if f: M + R3 is an immersion of such a surface, then f is proper and the image f(M) viewed from infinity looks like a finite collection of flat planes (with multiplicity) that pass through the origin. For example, the catenoid viewed from infinity looks like two oppositely oriented copies of a plane passing through the origin. Theorem 1 has a natural generalization to submanifolds of arbitrary codimension in R”. This generalization which is Theorem 2 is discussed in