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Torsion points in families of Drinfeld modules

Dragos Ghioca, Liang-Chung Hsia (2013)

Acta Arithmetica

Let Φ λ be an algebraic family of Drinfeld modules defined over a field K of characteristic p, and let a,b ∈ K[λ]. Assume that neither a(λ) nor b(λ) is a torsion point for Φ λ for all λ. If there exist infinitely many λ ∈ K̅ such that both a(λ) and b(λ) are torsion points for Φ λ , then we show that for each λ ∈ K̅, a(λ) is torsion for Φ λ if and only if b(λ) is torsion for Φ λ . In the case a,b ∈ K, we prove in addition that a and b must be ̅ p -linearly dependent.

Torsion points on families of simple abelian surfaces and Pell's equation over polynomial rings (with an appendix by E. V. Flynn)

David Masser, Umberto Zannier (2015)

Journal of the European Mathematical Society

In recent papers we proved a special case of a variant of Pink’s Conjecture for a variety inside a semiabelian scheme: namely for any curve inside anything isogenous to a product of two elliptic schemes. Here we go beyond the elliptic situation by settling the crucial case of any simple abelian surface scheme defined over the field of algebraic numbers, thus confirming an earlier conjecture of Shou-Wu Zhang. This is of particular relevance in the topic, also in view of very recent counterexamples...

Torsors under tori and Néron models

Martin Bright (2011)

Journal de Théorie des Nombres de Bordeaux

Let R be a Henselian discrete valuation ring with field of fractions K . If X is a smooth variety over K and G a torus over K , then we consider X -torsors under G . If 𝒳 / R is a model of X then, using a result of Brahm, we show that X -torsors under G extend to 𝒳 -torsors under a Néron model of G if G is split by a tamely ramified extension of K . It follows that the evaluation map associated to such a torsor factors through reduction to the special fibre. In this way we can use the geometry of the special...

Transformation de Fourier homogène

Gérard Laumon (2003)

Bulletin de la Société Mathématique de France

Dans leur démonstration de la correspondance de Drinfeld-Langlands, Frenkel, Gaitsgory et Vilonen utilisent la transformation de Fourier géométrique, ce qui les oblige à travailler soit avec les faisceaux -adiques en caractéristique p > 0 , soit avec les 𝒟 -Modules en caractéristique 0 . En fait, ils n’utilisent cette transformation de Fourier géométrique que pour des faisceaux homogènes pour lesquels on s’attend à avoir une transformation de Fourier sur . L’objet de cette note est de proposer une telle...

Trivial points on towers of curves

Xavier Xarles (2013)

Journal de Théorie des Nombres de Bordeaux

In order to study the behavior of the points in a tower of curves, we introduce and study trivial points on towers of curves, and we discuss their finiteness over number fields. We relate the problem of proving that the only rational points are the trivial ones at some level of the tower, to the unboundeness of the gonality of the curves in the tower, which we show under some hypothesis.

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