Illumination number of 3-dimensional cap bodies

Fuente: arXiv
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Auteurs principaux: Arman, Andrii, Kaire, Jaskaran Singh, Prymak, Andriy
Format: Preprint
Publié: 2025
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author Arman, Andrii
Kaire, Jaskaran Singh
Prymak, Andriy
author_facet Arman, Andrii
Kaire, Jaskaran Singh
Prymak, Andriy
contents The illumination conjecture asserts that any convex body in $n$-dimensional Euclidean space can be illuminated by at most $2^n$ external light sources or parallel beams of light. Despite recent progress on the illumination conjecture, it remains open in general, as well as for specific classes of bodies. Bezdek, Ivanov, and Strachan showed that the conjecture holds for symmetric cap bodies in sufficiently high dimensions. Further, Ivanov and Strachan calculated the illumination number for the class of 3-dimensional centrally symmetric cap bodies to be 6. In this paper, we show that even the broader class of all 3-dimensional cap bodies has the same illumination number 6, in particular, the illumination conjecture holds for this class. The illuminating directions can be taken to be vertices of a regular tetrahedron, together with two special directions depending on the body. The proof is based on probabilistic arguments and integer linear programming.
format Preprint
id arxiv_https___arxiv_org_abs_2507_08712
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Illumination number of 3-dimensional cap bodies
Arman, Andrii
Kaire, Jaskaran Singh
Prymak, Andriy
Metric Geometry
Primary 52A15, Secondary 52A40, 52C17, 90C05
The illumination conjecture asserts that any convex body in $n$-dimensional Euclidean space can be illuminated by at most $2^n$ external light sources or parallel beams of light. Despite recent progress on the illumination conjecture, it remains open in general, as well as for specific classes of bodies. Bezdek, Ivanov, and Strachan showed that the conjecture holds for symmetric cap bodies in sufficiently high dimensions. Further, Ivanov and Strachan calculated the illumination number for the class of 3-dimensional centrally symmetric cap bodies to be 6. In this paper, we show that even the broader class of all 3-dimensional cap bodies has the same illumination number 6, in particular, the illumination conjecture holds for this class. The illuminating directions can be taken to be vertices of a regular tetrahedron, together with two special directions depending on the body. The proof is based on probabilistic arguments and integer linear programming.
title Illumination number of 3-dimensional cap bodies
topic Metric Geometry
Primary 52A15, Secondary 52A40, 52C17, 90C05
url https://arxiv.org/abs/2507.08712