Displaying similar documents to “Rational points of a curve which has a nontrivial automorphism”

Hurwitz spaces of genus 2 covers of an elliptic curve.

Ernst Kani (2003)

Collectanea Mathematica

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Let E be an elliptic curve over a field K of characteristic not equal to 2 and let N > 1 be an integer prime to char(K). The purpose of this paper is to construct the (two-dimensional) Hurwitz moduli space H (E/K,N,2) which classifies genus 2 covers of E of degree N and to show that it is closely related to the modular curve X(N) which parametrizes elliptic curves with level-N-structure. More precisely, we introduce the notion of a normalized genus 2 cover of E/K and show that...

Extension of maps defined on many fibres.

Miguel A. Barja, Juan Carlos Naranjo (1998)

Collectanea Mathematica

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Let S be a fibred surface. We prove that the existence of morphisms from non countably many fibres to curves implies, up to base change, the existence of a rational map from S to another surface fibred over the same base reflecting the properties of the original morphisms. Under some conditions of unicity base change is not needed and one recovers exactly the initial maps.