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JOURNALS // Doklady Rossijskoj Akademii Nauk. Mathematika, Informatika, Processy Upravlenia // Archive

Dokl. RAN. Math. Inf. Proc. Upr., 2023 Volume 513, Pages 66–70 (Mi danma417)

This article is cited in 2 papers

MATHEMATICS

On the finiteness of the set of generalized Jacobians with nontrivial torsion points over algebraic number fields

V. P. Platonovab, V. S. Zhgoonacd, G.V. Fedorovae

a Federal State Institution Scientific Research Institute for System Analysis of the Russian Academy of Sciences, Moscow, Russian Federation
b Steklov Mathematical Institute of Russian Academy of Sciences, Moscow, Russian Federation
c National Research University Higher School of Economics, Moscow, Russian Federation
d Moscow Institute of Physics and Technology (National Research University), Moscow, Russian Federation
e Lomonosov Moscow State University, Moscow, Russian Federation

Abstract: For a smooth projective curve $\mathcal{C}$ defined over algebraic number field $k$, we investigate the question of finiteness of the set of generalized Jacobians $J_m$ of a curve $\mathcal{C}$ associated with modules $m$ defined over $k$ such that a fixed divisor representing a class of finite order in the Jacobian $J$ of the curve $\mathcal{C}$ provides the torsion class in the generalized Jacobian $J_m$. Various results on the finiteness and infiniteness of the set of generalized Jacobians with the above property are obtained depending on the geometric conditions on the support of $m$, as well as on the conditions on the field $k$. These results were applied to the problem of the periodicity of a continuous fraction decomposition constructed in the field of formal power series $k((1/x))$, for the special elements of the field of functions $k(\tilde{\mathcal{C}})$ of the hyperelliptic curve $\tilde{\mathcal{C}}:y^2=f(x)$.

Keywords: Jacobian variety, generalized Jacobian, torsion points, continuous fractions, hyperelliptic curve.

UDC: 511.6

Received: 11.09.2023
Revised: 20.09.2023
Accepted: 05.10.2023

DOI: 10.31857/S2686954323700285


 English version:
Doklady Mathematics, 2023, 108:2, 382–386

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© Steklov Math. Inst. of RAS, 2025