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Displaying similar documents to “Projective normality of abelian varieties with a line bundle of type 2 ,

The Kodaira dimension of Siegel modular varieties of genus 3 or higher

Eric Schellhammer (2006)

Bollettino dell'Unione Matematica Italiana

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We consider the moduli space A pol ( n ) of (non-principally) polarised abelian varieties of genus g 3 with coprime polarisation and full level-n structure. Based upon the analysis of the Tits building in [S], we give an explicit lower bound on n that is sufficient for the compactified moduli space to be of general type if one further explicit condition is satisfied.

Theta height and Faltings height

Fabien Pazuki (2012)

Bulletin de la Société Mathématique de France

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Using original ideas from J.-B. Bost and S. David, we provide an explicit comparison between the Theta height and the stable Faltings height of a principally polarized Abelian variety. We also give as an application an explicit upper bound on the number of K -rational points of a curve of genus g 2 under a conjecture of S. Lang and J. Silverman. We complete the study with a comparison between differential lattice structures.

On a generalization of Abelian sequential groups

Saak S. Gabriyelyan (2013)

Fundamenta Mathematicae

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Let (G,τ) be a Hausdorff Abelian topological group. It is called an s-group (resp. a bs-group) if there is a set S of sequences in G such that τ is the finest Hausdorff (resp. precompact) group topology on G in which every sequence of S converges to zero. Characterizations of Abelian s- and bs-groups are given. If (G,τ) is a maximally almost periodic (MAP) Abelian s-group, then its Pontryagin dual group ( G , τ ) is a dense -closed subgroup of the compact group ( G d ) , where G d is the group G with...

Asymptotics of eigensections on toric varieties

A. Huckleberry, H. Sebert (2013)

Annales de l’institut Fourier

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Using exhaustion properties of invariant plurisubharmonic functions along with basic combinatorial information on toric varieties, we prove convergence results for sequences of densities | ϕ n | 2 = | s N | 2 / | | s N | | L 2 2 for eigensections s N Γ ( X , L N ) approaching a semiclassical ray. Here X is a normal compact toric variety and L is an ample line bundle equipped with an arbitrary positive bundle metric which is invariant with respect to the compact form of the torus. Our work was motivated by and extends that of Shiffman, Tate...

Some Remarks on Prym-Tyurin Varieties

Giuliano Parigi (2007)

Bollettino dell'Unione Matematica Italiana

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The aims of the present paper can be described as follows: a) In [2] Beauville showed that if some endomorphism u a Jacobian J ( C ) has connected kernel, the principal polarization on J ( C ) induces a multiple of the principal polarization on the image of u . We reformulate and complete this theorem proving "constructively" the following: Theorem. Let Z J ( C ) be an abelian subvariety and Y its complementary variety. Z is a Prym-Tyurin variety with respect to J ( C ) if and only if the following sequence...

Some topological conditions for projective algebraic manifolds with degenerate dual varieties: connections with 𝐏 -bundles

Antonio Lanteri, Daniele Struppa (1984)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

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Si illustrano alcune relazioni tra le varietà proiettive complesse con duale degenere, le varietà la cui topologia si riflette in quella della sezione iperpiana in misura maggiore dell'ordinario e le varietà fibrate in spazi lineari su di una curva.

Pseudo-abelian varieties

Burt Totaro (2013)

Annales scientifiques de l'École Normale Supérieure

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Chevalley’s theorem states that every smooth connected algebraic group over a perfect field is an extension of an abelian variety by a smooth connected affine group. That fails when the base field is not perfect. We define a pseudo-abelian variety over an arbitrary field k to be a smooth connected k -group in which every smooth connected affine normal k -subgroup is trivial. This gives a new point of view on the classification of algebraic groups: every smooth connected group over a field...

Lagrangian fibrations on generalized Kummer varieties

Martin G. Gulbrandsen (2007)

Bulletin de la Société Mathématique de France

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We investigate the existence of Lagrangian fibrations on the generalized Kummer varieties of Beauville. For a principally polarized abelian surface A of Picard number one we find the following: The Kummer variety K n A is birationally equivalent to another irreducible symplectic variety admitting a Lagrangian fibration, if and only if n is a perfect square. And this is the case if and only if K n A carries a divisor with vanishing Beauville-Bogomolov square.

Polarizations of Prym varieties for Weyl groups via abelianization

Herbert Lange, Christian Pauly (2009)

Journal of the European Mathematical Society

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Let π : Z X be a Galois covering of smooth projective curves with Galois group the Weyl group of a simple and simply connected Lie group G . For any dominant weight λ consider the curve Y = Z / Stab ( λ ) . The Kanev correspondence defines an abelian subvariety P λ of the Jacobian of Y . We compute the type of the polarization of the restriction of the canonical principal polarization of Jac ( Y ) to P λ in some cases. In particular, in the case of the group E 8 we obtain families of Prym-Tyurin varieties. The main idea is...

The boundedness of singular subvarieties of P N not of a general type and with low codimension

E. Ballico (2000)

Bollettino dell'Unione Matematica Italiana

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Sia X P N una varietà irriducibile n -dimensionale localmente Cohen-Macaulay, Q -Gorenstein e non di tipo generale; assumiamo N = 6 , 2 n = N + 2 e dim Sing X = 2 n - N . In questo lavoro dimostriamo che deg X N + 1 N - n e quindi che l'insieme di tutte queste varietà è parametrizzato da un insieme finito di varietà algebriche.

Singularities of theta divisors and the geometry of 𝒜 5

Gavril Farkas, Samuele Grushevsky, Salvati R. Manni, Alessandro Verra (2014)

Journal of the European Mathematical Society

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We study the codimension two locus H in 𝒜 g consisting of principally polarized abelian varieties whose theta divisor has a singularity that is not an ordinary double point. We compute the class [ H ] C H 2 ( 𝒜 g ) for every g . For g = 4 , this turns out to be the locus of Jacobians with a vanishing theta-null. For g = 5 , via the Prym map we show that H 𝒜 5 has two components, both unirational, which we describe completely. We then determine the slope of the effective cone of 𝒜 5 ¯ and show that the component N 0 ' ¯ of the Andreotti-Mayer...

Hodge Classes and Abelian Varieties of Quaternionic Type

Giuseppe Lombardo (2006)

Bollettino dell'Unione Matematica Italiana

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We obtain coniugacy classes (with respect to a 𝔰 l 2 action) in the space of Hodge cycles in the middle cohomology of an Abelian variety of quaternionic type. The existence of such a class simplifies the study of the Hodge conjecture.

Some topological conditions for projective algebraic manifolds with degenerate dual varieties: connections with 𝐏 -bundles

Antonio Lanteri, Daniele Struppa (1984)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

Similarity:

Si illustrano alcune relazioni tra le varietà proiettive complesse con duale degenere, le varietà la cui topologia si riflette in quella della sezione iperpiana in misura maggiore dell'ordinario e le varietà fibrate in spazi lineari su di una curva.

Number of solutions in a box of a linear equation in an Abelian group

Maciej Zakarczemny (2016)

Colloquium Mathematicae

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For every finite Abelian group Γ and for all g , a , . . . , a k Γ , if there exists a solution of the equation i = 1 k a i x i = g in non-negative integers x i b i , where b i are positive integers, then the number of such solutions is estimated from below in the best possible way.

Line bundles with partially vanishing cohomology

Burt Totaro (2013)

Journal of the European Mathematical Society

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Define a line bundle L on a projective variety to be q -ample, for a natural number q , if tensoring with high powers of L kills coherent sheaf cohomology above dimension q . Thus 0-ampleness is the usual notion of ampleness. We show that q -ampleness of a line bundle on a projective variety in characteristic zero is equivalent to the vanishing of an explicit finite list of cohomology groups. It follows that q -ampleness is a Zariski open condition, which is not clear from the definition. ...

Essential dimension of moduli of curves and other algebraic stacks

Patrick Brosnan, Zinovy Reichstein, Angelo Vistoli (2011)

Journal of the European Mathematical Society

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In this paper we consider questions of the following type. Let k be a base field and K / k be a field extension. Given a geometric object X over a field K (e.g. a smooth curve of genus g ), what is the least transcendence degree of a field of definition of X over the base field k ? In other words, how many independent parameters are needed to define X ? To study these questions we introduce a notion of essential dimension for an algebraic stack. Using the resulting theory, we give a complete...

A boundedness theorem for morphisms between threefolds

Ekatarina Amerik, Marat Rovinsky, Antonius Van de Ven (1999)

Annales de l'institut Fourier

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The main result of this paper is as follows: let X , Y be smooth projective threefolds (over a field of characteristic zero) such that b 2 ( X ) = b 2 ( Y ) = 1 . If Y is not a projective space, then the degree of a morphism f : X Y is bounded in terms of discrete invariants of X and Y . Moreover, suppose that X and Y are smooth projective n -dimensional with cyclic Néron-Severi groups. If c 1 ( Y ) = 0 , then the degree of f is bounded iff Y is not a flat variety. In particular, to prove our main theorem we show the non-existence of...