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arXiv · 2308.03889

Borsuk and Vázsonyi problems through Reuleaux polyhedra

Gyivan Lopez-Campos·Deborah Oliveros·Jorge L. Ramírez Alfonsín
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Abstract

The Borsuk conjecture and the Vázsonyi problem are two attractive and famous questions in discrete and combinatorial geometry, both based on the notion of diameter of a bounded sets. In this paper, we present an equivalence between the critical sets with Borsuk number 4 in $\mathbb{R}^3$ and the minimal structures for the Vázsonyi problem by using the well-known Reuleaux polyhedra. The latter lead to a full characterization of all finite sets in $\mathbb{R}^3$ with Borsuk number 4. The proof of such equivalence needs various ingredients, in particular, we proved a conjecture dealing with strongly critical configuration for the Vázsonyi problem and showed that the diameter graph arising from involutive polyhedra is vertex (and edge) 4-critical.

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Gyivan Lopez-Campos, Deborah Oliveros, Jorge L. Ramírez Alfonsín. 2025-07-22. Borsuk and Vázsonyi problems through Reuleaux polyhedra. https://doi.org/10.1016/j.ejc.2025.104215

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