In 1960 Reifenberg proved the topological disc property. He showed that a subset of R-n which is well approximated by m-dimensional affine spaces at each point and at each (small) scale is locally a bi-Holder image of the unit ball in R-m. In this paper we prove that a subset of R-3 which is well approximated in the Hausdorff distance sense by one of the three standard area-minimizing cones at each point and at each (small) scale is locally a bi-Holder deformation of a minimal cone. We also prove an analogous result for more general cones in R-n.
David, G., De Pauw, T., & Toro, T. (2008). A Generalization of Reifenberg’s Theorem in R-3. Geometric and functional analysis, 18(4), 1168-1235. https://doi.org/10.1007/s00039-008-0681-8 (Original work published 2008)