On Frobenius' Theta Formula

Mumford's well-known characterization of the hyperelliptic locus of the moduli space of ppavs in terms of vanishing and non-vanishing theta constants is based on Neumann's dynamical system. Poor's approach to the characterization uses the cross ratio. A key tool in both methods is Fro...

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Published in:Symmetry, Integrability and Geometry: Methods and Applications
Date:2020
Main Authors: Fiorentino, Alessio, Salvati Manni, Riccardo
Format: Article
Language:English
Published: Інститут математики НАН України 2020
Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/210693
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Journal Title:Digital Library of Periodicals of National Academy of Sciences of Ukraine
Cite this:On Frobenius' Theta Formula. Alessio Fiorentino and Riccardo Salvati Manni. SIGMA 16 (2020), 057, 14 pages

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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author Fiorentino, Alessio
Salvati Manni, Riccardo
author_facet Fiorentino, Alessio
Salvati Manni, Riccardo
citation_txt On Frobenius' Theta Formula. Alessio Fiorentino and Riccardo Salvati Manni. SIGMA 16 (2020), 057, 14 pages
collection DSpace DC
container_title Symmetry, Integrability and Geometry: Methods and Applications
description Mumford's well-known characterization of the hyperelliptic locus of the moduli space of ppavs in terms of vanishing and non-vanishing theta constants is based on Neumann's dynamical system. Poor's approach to the characterization uses the cross ratio. A key tool in both methods is Frobenius' theta formula, which follows from Riemann's theta formula. In a 2004 paper, Grushevsky gives a different characterization in terms of cubic equations in second-order theta functions. In this note, we first show the connection between the methods by proving that Grushevsky's cubic equations are strictly related to Frobenius' theta formula, and we then give a new proof of Mumford's characterization via Gunning's multisecant formula.
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institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
issn 1815-0659
language English
last_indexed 2025-12-17T12:03:39Z
publishDate 2020
publisher Інститут математики НАН України
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spelling Fiorentino, Alessio
Salvati Manni, Riccardo
2025-12-15T15:18:28Z
2020
On Frobenius' Theta Formula. Alessio Fiorentino and Riccardo Salvati Manni. SIGMA 16 (2020), 057, 14 pages
1815-0659
2020 Mathematics Subject Classification: 14H42; 14H45; 14K25; 14K12; 14H40
arXiv:2004.05099
https://nasplib.isofts.kiev.ua/handle/123456789/210693
https://doi.org/10.3842/SIGMA.2020.057
Mumford's well-known characterization of the hyperelliptic locus of the moduli space of ppavs in terms of vanishing and non-vanishing theta constants is based on Neumann's dynamical system. Poor's approach to the characterization uses the cross ratio. A key tool in both methods is Frobenius' theta formula, which follows from Riemann's theta formula. In a 2004 paper, Grushevsky gives a different characterization in terms of cubic equations in second-order theta functions. In this note, we first show the connection between the methods by proving that Grushevsky's cubic equations are strictly related to Frobenius' theta formula, and we then give a new proof of Mumford's characterization via Gunning's multisecant formula.
The authors would like to thank Bert van Geemen for drawing their attention to the result in [5]. They are also grateful to Sam Grushevsky for many helpful discussions and explanations. The authors are greatly indebted to an anonymous referee for the careful reading and suggestions.
en
Інститут математики НАН України
Symmetry, Integrability and Geometry: Methods and Applications
On Frobenius' Theta Formula
Article
published earlier
spellingShingle On Frobenius' Theta Formula
Fiorentino, Alessio
Salvati Manni, Riccardo
title On Frobenius' Theta Formula
title_full On Frobenius' Theta Formula
title_fullStr On Frobenius' Theta Formula
title_full_unstemmed On Frobenius' Theta Formula
title_short On Frobenius' Theta Formula
title_sort on frobenius' theta formula
url https://nasplib.isofts.kiev.ua/handle/123456789/210693
work_keys_str_mv AT fiorentinoalessio onfrobeniusthetaformula
AT salvatimanniriccardo onfrobeniusthetaformula