Alexandrov--Fenchel inequalities for convex domains in the sphere
Abstract
We prove the Alexandrov--Fenchel inequalities between any two spherical quermassintegrals for smooth weakly convex domains contained in an open hemisphere, with equality if and only if the domain is a geodesic ball. For strictly convex hypersurfaces, we introduce a globally constrained curvature flow which preserves one quermassintegral and decreases the next one. We establish uniform curvature estimates by combining a pinching estimate, a support function argument, and spherical polarity. As a consequence, the flow exists for all time and converges smoothly and exponentially to a geodesic sphere. The monotonicity of the quermassintegrals gives the full family of Alexandrov--Fenchel inequalities. A short-time mean curvature flow approximation and a localized rigidity argument extend the result, including the equality characterization, to weakly convex domains.
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BibTeX
@misc{luo2026alexandrovfenchel,
title = {{Alexandrov--Fenchel inequalities for convex domains in the sphere}},
author = {Tianci Luo and Yong Wei and Rong Zhou},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.13829},
eprint = {2609.13829},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.13829},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Alexandrov--Fenchel inequalities for convex domains in the sphere
AU - Tianci Luo
AU - Yong Wei
AU - Rong Zhou
PY - 2026
DA - 2026/09/12
PB - arXiv
DO - 10.48550/arxiv.2609.13829
UR - https://arxiv.org/abs/2609.13829
AB - We prove the Alexandrov--Fenchel inequalities between any two spherical quermassintegrals for smooth weakly convex domains contained in an open hemisphere, with equality if and only if the domain is a geodesic ball. For strictly convex hypersurfaces, we introduce a globally constrained curvature flow which preserves one quermassintegral and decreases the next one. We establish uniform curvature estimates by combining a pinching estimate, a support function argument, and spherical polarity. As a consequence, the flow exists for all time and converges smoothly and exponentially to a geodesic sphere. The monotonicity of the quermassintegrals gives the full family of Alexandrov--Fenchel inequalities. A short-time mean curvature flow approximation and a localized rigidity argument extend the result, including the equality characterization, to weakly convex domains.
ER -