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Main Authors: Chan, Daniel, Nyman, Adam
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.09825
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author Chan, Daniel
Nyman, Adam
author_facet Chan, Daniel
Nyman, Adam
contents Let $k$ denote an algebraically closed field of characteristic zero and let $X$ denote a smooth elliptic curve over $k$. In this paper, motivated by work in \cite{CN}, we think of two-periodic elliptic helices as noncommutative analogues of degree two line bundles over $X$. We classify and study two-periodic elliptic helices in order to generalize the theory of double covers of $\mathbb{P}^{1}$ by $X$ to the noncommutative setting. This leads to the following problem: given an integer $d>2$ and a real number $θ\in \mathbb{Q}+\mathbb{Q}\sqrt{d^2-4}$, classify elliptic helices inducing double covers of $\mathbb{P}^{1}_{d}$ by ${\sf C}^θ$, where $\mathbb{P}^{1}_{d}$ is Piontkovski's noncommutative projective line and ${\sf C}^θ$ is Polischuk's noncommutative elliptic curve. We find examples of $d$ and $θ$ such that there is essentially one numerical class of elliptic helices and examples of $d$ and $θ$ such that there are several distinct numerical classes of elliptic helices, in contrast to the commutative situation.
format Preprint
id arxiv_https___arxiv_org_abs_2511_09825
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Two-periodic elliptic helices: classification and geometry
Chan, Daniel
Nyman, Adam
Algebraic Geometry
Rings and Algebras
Primary 14A22, Secondary 16S38
Let $k$ denote an algebraically closed field of characteristic zero and let $X$ denote a smooth elliptic curve over $k$. In this paper, motivated by work in \cite{CN}, we think of two-periodic elliptic helices as noncommutative analogues of degree two line bundles over $X$. We classify and study two-periodic elliptic helices in order to generalize the theory of double covers of $\mathbb{P}^{1}$ by $X$ to the noncommutative setting. This leads to the following problem: given an integer $d>2$ and a real number $θ\in \mathbb{Q}+\mathbb{Q}\sqrt{d^2-4}$, classify elliptic helices inducing double covers of $\mathbb{P}^{1}_{d}$ by ${\sf C}^θ$, where $\mathbb{P}^{1}_{d}$ is Piontkovski's noncommutative projective line and ${\sf C}^θ$ is Polischuk's noncommutative elliptic curve. We find examples of $d$ and $θ$ such that there is essentially one numerical class of elliptic helices and examples of $d$ and $θ$ such that there are several distinct numerical classes of elliptic helices, in contrast to the commutative situation.
title Two-periodic elliptic helices: classification and geometry
topic Algebraic Geometry
Rings and Algebras
Primary 14A22, Secondary 16S38
url https://arxiv.org/abs/2511.09825