An index formula for hemispheres of a $C^2$-regular convex closed surface in Euclidean $3$-space

Fuente: arXiv
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Main Authors: Ando, Naoya, Umehara, Masaaki
Format: Preprint
Published: 2025
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author Ando, Naoya
Umehara, Masaaki
author_facet Ando, Naoya
Umehara, Masaaki
contents Carathéodory's conjecture has long been regarded as one of the central problems in the classical theory of convex surfaces. In this paper, we establish an index formula for hemispheres of convex closed surfaces under $C^2$-regularity. The proof is based on studying a vertical section of the null hypersurfaces in Lorentz--Minkowski $4$-space associated with the originally given convex surface. As a consequence, the conjecture is affirmatively solved in the $C^2$-case.
format Preprint
id arxiv_https___arxiv_org_abs_2512_23181
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An index formula for hemispheres of a $C^2$-regular convex closed surface in Euclidean $3$-space
Ando, Naoya
Umehara, Masaaki
Differential Geometry
Carathéodory's conjecture has long been regarded as one of the central problems in the classical theory of convex surfaces. In this paper, we establish an index formula for hemispheres of convex closed surfaces under $C^2$-regularity. The proof is based on studying a vertical section of the null hypersurfaces in Lorentz--Minkowski $4$-space associated with the originally given convex surface. As a consequence, the conjecture is affirmatively solved in the $C^2$-case.
title An index formula for hemispheres of a $C^2$-regular convex closed surface in Euclidean $3$-space
topic Differential Geometry
url https://arxiv.org/abs/2512.23181