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Remarks on strongly modular Jacobian surfaces

Xavier Guitart, Jordi Quer (2011)

Journal de Théorie des Nombres de Bordeaux

In [3] we introduced the concept of strongly modular abelian variety. This note contains some remarks and examples of this kind of varieties, especially for the case of Jacobian surfaces, that complement the results of [3].

Semistable reduction and torsion subgroups of abelian varieties

Alice Silverberg, Yuri G. Zarhin (1995)

Annales de l'institut Fourier

The main result of this paper implies that if an abelian variety over a field F has a maximal isotropic subgroup of n -torsion points all of which are defined over F , and n 5 , then the abelian variety has semistable reduction away from n . This result can be viewed as an extension of Raynaud’s theorem that if an abelian variety and all its n -torsion points are defined over a field F and n 3 , then the abelian variety has semistable reduction away from n . We also give information about the Néron models...

Sign functions of imaginary quadratic fields and applications

Hassan Oukhaba (2005)

Annales de l’institut Fourier

We propose a definition of sign of imaginary quadratic fields. We give an example of such functions, and use it to define new invariants that are roots of the classical Ramachandra invariants. Also we introduce signed ordinary distributions and compute their signed cohomology by using Anderson's theory of double complex.

Simple exponential estimate for the number of real zeros of complete abelian integrals

Dmitri Novikov, Sergei Yakovenko (1995)

Annales de l'institut Fourier

We show that for a generic polynomial H = H ( x , y ) and an arbitrary differential 1-form ω = P ( x , y ) d x + Q ( x , y ) d y with polynomial coefficients of degree d , the number of ovals of the foliation H = const , which yield the zero value of the complete Abelian integral I ( t ) = H = t ω , grows at most as exp O H ( d ) as d , where O H ( d ) depends only on H . The main result of the paper is derived from the following more general theorem on bounds for isolated zeros occurring in polynomial envelopes of linear differential equations. Let f 1 ( t ) , , f n ( t ) , t K , be a fundamental system of real solutions...

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