Cubulating the sphere with many facets

Fuente: arXiv
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Main Authors: Avvakumov, Sergey, Hubard, Alfredo
Format: Preprint
Published: 2025
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author Avvakumov, Sergey
Hubard, Alfredo
author_facet Avvakumov, Sergey
Hubard, Alfredo
contents For each $d\geq 3$ we construct cube complexes homeomorphic to the $d$-sphere with $n$ vertices in which the number of facets (assuming $d$ constant) is $Ω(n^{5/4})$. This disproves a conjecture of Kalai's stating that the number of faces (of all dimensions) of cubical spheres is maximized by the boundaries of neighbourly cubical polytopes. The conjecture was already known to be false for $d=3$, $n=64$. Our construction disproves it for all $d\geq 3$ and $n$ sufficiently large. Moreover, since neighborly cubical polytopes have roughly $n (\log n)^{d/2}$ facets, we show that even the order of growth (at least for the number of facets) in the conjecture is wrong.
format Preprint
id arxiv_https___arxiv_org_abs_2503_18047
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Cubulating the sphere with many facets
Avvakumov, Sergey
Hubard, Alfredo
Combinatorics
Geometric Topology
For each $d\geq 3$ we construct cube complexes homeomorphic to the $d$-sphere with $n$ vertices in which the number of facets (assuming $d$ constant) is $Ω(n^{5/4})$. This disproves a conjecture of Kalai's stating that the number of faces (of all dimensions) of cubical spheres is maximized by the boundaries of neighbourly cubical polytopes. The conjecture was already known to be false for $d=3$, $n=64$. Our construction disproves it for all $d\geq 3$ and $n$ sufficiently large. Moreover, since neighborly cubical polytopes have roughly $n (\log n)^{d/2}$ facets, we show that even the order of growth (at least for the number of facets) in the conjecture is wrong.
title Cubulating the sphere with many facets
topic Combinatorics
Geometric Topology
url https://arxiv.org/abs/2503.18047