A compact minimal shadow boundary in Euclidean space is totally geodesic
We prove that a compact minimal shadow boundary of a hypersurface in Euclidean space is totally geodesic. We show that shadow boundaries detect principal directions and umbilical points of a hypersurface. As application we deduce that every shadow boundary of a compact strictly convex surface contai...
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Veröffentlicht in: | Monatshefte für Mathematik 2012-11, Vol.168 (2), p.183-189 |
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Hauptverfasser: | , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | We prove that a compact minimal shadow boundary of a hypersurface in Euclidean space is totally geodesic. We show that shadow boundaries detect principal directions and umbilical points of a hypersurface. As application we deduce that every shadow boundary of a compact strictly convex surface contains at least two principal directions. |
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ISSN: | 0026-9255 1436-5081 |
DOI: | 10.1007/s00605-011-0352-y |