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The monodromy conjecture for zeta functions associated to ideals in dimension two

Lise Van Proeyen, Willem Veys (2010)

Annales de l’institut Fourier

The monodromy conjecture states that every pole of the topological (or related) zeta function induces an eigenvalue of monodromy. This conjecture has already been studied a lot. However in full generality it is proven only for zeta functions associated to polynomials in two variables.In this article we work with zeta functions associated to an ideal. First we work in arbitrary dimension and obtain a formula (like the one of A’Campo) to compute the “Verdier monodromy” eigenvalues associated to an...

The Mumford conjecture

Geoffrey Powell (2004/2005)

Séminaire Bourbaki

The Mumford Conjecture asserts that the rational cohomology of the stable moduli space of Riemann surfaces is a polynomial algebra on the Mumford-Morita-Miller characteristic classes; this can be reformulated in terms of the classifying space B Γ derived from the mapping class groups. The conjecture admits a topological generalization, inspired by Tillmann’s theorem that B Γ admits an infinite loop space structure after applying Quillen’s plus construction. The text presents the proof by Madsen and...

The optimality of the Bounded Height Conjecture

Evelina Viada (2009)

Journal de Théorie des Nombres de Bordeaux

In this article we show that the Bounded Height Conjecture is optimal in the sense that, if V is an irreducible subvariety with empty deprived set in a power of an elliptic curve, then every open subset of V does not have bounded height. The Bounded Height Conjecture is known to hold. We also present some examples and remarks.

The p -part of Tate-Shafarevich groups of elliptic curves can be arbitrarily large

Remke Kloosterman (2005)

Journal de Théorie des Nombres de Bordeaux

In this paper we show that for every prime p 5 the dimension of the p -torsion in the Tate-Shafarevich group of E / K can be arbitrarily large, where E is an elliptic curve defined over a number field K , with [ K : ] bounded by a constant depending only on p . From this we deduce that the dimension of the p -torsion in the Tate-Shafarevich group of A / can be arbitrarily large, where A is an abelian variety, with dim A bounded by a constant depending only on p .

The p -rank stratification of Artin-Schreier curves

Rachel Pries, Hui June Zhu (2012)

Annales de l’institut Fourier

We study a moduli space 𝒜𝒮 g for Artin-Schreier curves of genus g over an algebraically closed field k of characteristic p . We study the stratification of 𝒜𝒮 g by p -rank into strata 𝒜𝒮 g . s of Artin-Schreier curves of genus g with p -rank exactly s . We enumerate the irreducible components of 𝒜𝒮 g , s and find their dimensions. As an application, when p = 2 , we prove that every irreducible component of the moduli space of hyperelliptic k -curves with genus g and 2 -rank s has dimension g - 1 + s . We also determine all pairs ( p , g ) for...

The Picard group of a coarse moduli space of vector bundles in positive characteristic

Norbert Hoffmann (2012)

Open Mathematics

Let C be a smooth projective curve over an algebraically closed field of arbitrary characteristic. Let M r,Lss denote the projective coarse moduli scheme of semistable rank r vector bundles over C with fixed determinant L. We prove Pic(M r,Lss) = ℤ, identify the ample generator, and deduce that M r,Lss is locally factorial. In characteristic zero, this has already been proved by Drézet and Narasimhan. The main point of the present note is to circumvent the usual problems with Geometric Invariant...

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