On the convex hull of integer points above the hyperbola

Fuente: arXiv
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Main Authors: Alcántara, David, Blanco, Mónica, Criado, Francisco, Santos, Francisco
Format: Preprint
Published: 2025
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author Alcántara, David
Blanco, Mónica
Criado, Francisco
Santos, Francisco
author_facet Alcántara, David
Blanco, Mónica
Criado, Francisco
Santos, Francisco
contents We show that the polyhedron defined as the convex hull of the lattice points above the hyperbola $\left\{xy = n\right\}$ has between $Ω(n^{1/3})$ and $O(n^{1/3} \log n)$ vertices. The same bounds apply to any hyperbola with rational slopes except that instead of $n$ we have $n/Δ$ in the lower bound and by $\max\left\{Δ, n/Δ\right\}$ in the upper bound, where $Δ\in \mathbb{Z}_{>0}$ is the discriminant. We also give an algorithm that enumerates the vertices of these convex hulls in logarithmic time per vertex. One motivation for such an algorithm is the deterministic factorization of integers.
format Preprint
id arxiv_https___arxiv_org_abs_2501_19193
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the convex hull of integer points above the hyperbola
Alcántara, David
Blanco, Mónica
Criado, Francisco
Santos, Francisco
Combinatorics
Computational Geometry
52C05, 52C45, 68R99, 52-08
I.3.5
We show that the polyhedron defined as the convex hull of the lattice points above the hyperbola $\left\{xy = n\right\}$ has between $Ω(n^{1/3})$ and $O(n^{1/3} \log n)$ vertices. The same bounds apply to any hyperbola with rational slopes except that instead of $n$ we have $n/Δ$ in the lower bound and by $\max\left\{Δ, n/Δ\right\}$ in the upper bound, where $Δ\in \mathbb{Z}_{>0}$ is the discriminant. We also give an algorithm that enumerates the vertices of these convex hulls in logarithmic time per vertex. One motivation for such an algorithm is the deterministic factorization of integers.
title On the convex hull of integer points above the hyperbola
topic Combinatorics
Computational Geometry
52C05, 52C45, 68R99, 52-08
I.3.5
url https://arxiv.org/abs/2501.19193