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In this paper we consider the Prym map for double coverings of curves of genus $g$ ramified at $r>0$ points. That is, the map associating to a double ramified covering its Prym variety. The generic Torelli theorem states that the Prym map…

Algebraic Geometry · Mathematics 2021-04-20 Juan Carlos Naranjo , Angela Ortega , Alesandro Verra

We study the ramified Prym map $\mathcal P_{g,r} \longrightarrow \mathcal A_{g-1+\frac r2}^{\delta}$ which assigns to a ramified double cover of a smooth irreducible curve of genus $g$ ramified in $r$ points the Prym variety of the…

Algebraic Geometry · Mathematics 2021-05-10 P. Frediani , J. C. Naranjo , I. Spelta

We prove the generic injectivity of the Prym map, sending a double covering of an elliptic curve ramified at r>4 points to its polarized Prym variety. For r=6 the map is birational.

Algebraic Geometry · Mathematics 2011-11-15 Valeria Ornella Marcucci , Juan Carlos Naranjo

In this paper we prove that the Prym map, from the space of double coverings of a curve of genus g with r branch points to the moduli space of abelian varieties, is generically injective if r>6 and g>1, r=6 and g>2, r=4 and g>4, r=2 and…

Algebraic Geometry · Mathematics 2019-02-20 Valeria Ornella Marcucci , Gian Pietro Pirola

We prove that the moduli space of double covers ramified at two points $\mathcal{R}_{g,2}$ is uniruled for $3\leq g\leq 6$ and of general type for $g\geq 16$. Furthermore, we consider Prym-canonical divisorial strata in the moduli space…

Algebraic Geometry · Mathematics 2021-05-03 Andrei Bud

The aim of this paper to prove that the ramified Prym map restricted to the locus of coverings of quintic plane curves ramified in 2 points is generically injective.

Algebraic Geometry · Mathematics 2023-04-19 Juan Carlos Naranjo , Irene Spelta

The Prym map assigns to each covering of curves a polarized abelian variety. In the case of unramified cyclic covers of curves of genus two, we show that the Prym map is ramified precisely on the locus of bielliptic covers. The key…

Algebraic Geometry · Mathematics 2024-06-19 Daniele Agostini

The Prym map of type (g,n,r) associates to every cyclic covering of degree n of a curve of genus g, ramified at a reduced divisor of degree r, the corresponding Prym variety. We show that the corresponding map of moduli spaces is…

Algebraic Geometry · Mathematics 2008-05-08 H. Lange , A. Ortega

To any unramified double cover $\pi:\tilde C \to C$ of projective irreducible and nonsingular curves one associates the Prym variety $P = P(\pi)$. For $C$ nonhyperelliptic of genus $g \geq 6$ we consider the natural embedding $\tilde C…

Algebraic Geometry · Mathematics 2016-09-07 Herbert Lange , Edoardo Sernesi

We study Shimura curves of PEL type in the space of polarised abelian varieties $A^{\delta}_p$ generically contained in the ramified Prym locus. We generalise to ramified double covers, the construction done in [10] in the unramified case…

Algebraic Geometry · Mathematics 2020-07-21 Paola Frediani , Gian Paolo Grosselli

To every double cover ramified in two points of a general trigonal curve of genus g, one can associate an \'etale double cover of a tetragonal curve of genus g+1. We show that the corresponding Prym varieties are canonically isomorphic as…

Algebraic Geometry · Mathematics 2019-02-04 Herbert Lange , Angela Ortega

The Prym variety for a branched double covering of a nonsingular projective curve is defined as a polarized abelian variety. We prove that any double covering of an elliptic curve which has more than $4$ branch points is recovered from its…

Algebraic Geometry · Mathematics 2018-12-20 Atsushi Ikeda

We study unramified Galois $\mathbb{Z}_3 \times \mathbb{Z}_3$ coverings of genus 2 curves and the corresponding Prym varieties and Prym maps. In particular, we prove that any such covering can be reconstructed from its Prym variety, that…

Algebraic Geometry · Mathematics 2026-02-24 Paweł Borówka , Anatoli Shatsila

In this paper we study the second fundamental form of the Prym map $P_{g,r}: R_{g,r} \rightarrow {\mathcal A}^{\delta}_{g-1+r}$ in the ramified case $r>0$. We give an expression of it in terms of the second fundamental form of the Torelli…

Algebraic Geometry · Mathematics 2019-08-14 Elisabetta Colombo , Paola Frediani

We initiate the study of Prym-Brill-Noether theory for ramified double covers, extending several key results from classical Prym-Brill-Noether theory to this new framework. In particular, we improve Kanev's results on the dimension of…

Algebraic Geometry · Mathematics 2024-11-04 Andrei Bud

We prove that the Prym map corresponding to \'etale cyclic coverings of hyperelliptic curves is injective whenever the degree of the covering $d \geq 6$ is not a power of an odd prime. For other degrees $d\geq 9$, we show that the Prym map…

Algebraic Geometry · Mathematics 2025-12-25 Paweł Borówka , Juan Carlos Naranjo , Angela Ortega , Anatoli Shatsila

We study Shimura curves of PEL type in $\mathsf{A}_g$ generically contained in the Prym locus. We study both the unramified Prym locus, obtained using \'etale double covers, and the ramified Prym locus, corresponding to double covers…

Algebraic Geometry · Mathematics 2018-01-16 Elisabetta Colombo , Paola Frediani , Alessandro Ghigi , Matteo Penegini

In this paper, we study the Prym map associated to degree 4 \'etale cyclic covers of genus $g$ hyperelliptic curves restricted to the irreducible component $\mathcal{RH}_g[4]^{hyp}$ of the moduli space of such covers where an intermediate…

Algebraic Geometry · Mathematics 2026-03-26 Anatoli Shatsila

If $\pi: Y \to X$ is an unramified double cover of a smooth curve of genus $g$, then the Prym variety $P_\pi$ is a principally polarized abelian variety of dimension $g-1$. When $X$ is defined over an algebraically closed field $k$ of…

Number Theory · Mathematics 2017-08-15 Turku Ozlum Celik , Yara Elias , Burcin Gunes , Rachel Newton , Ekin Ozman , Rachel Pries , Lara Thomas

We study Prym varieties of ramified (at precisely two points) double covers of smooth irreducible complex projectives curves that admit an automorphism of prime order $p>2$. Using Galois theory, we give an explicit constructions of Prym…

Algebraic Geometry · Mathematics 2026-05-26 Yuri G. Zarhin
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