The geometry of flat isometric immersions
arXiv:2001.11000
Abstract
We show that any isometric immersion of a flat plane domain into is developable provided it enjoys the little Hölder regulairty . In particular, isometric immersions of local regularity with belong to this class. The proof is based on the existence of a weak notion of second fundamental form for such immersions, the analysis of the Gauss-Codazzi-Mainardi equations in this weak setting, and a parallel result on the very weak solutions to the degenerate Monge-Ampère equation analyzed by Lewicka and the second author.
31 pages; Minor editorial corrections with respect to v4. To appear in Proceedings of the Royal Society of Edinburgh Section A