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

Eric Schellhammer

Displaying similar documents to “The Kodaira dimension of Siegel modular varieties of genus 3 or higher”

The Kodaira dimension of the moduli space of Prym varieties

Gavril Farkas, Katharina Ludwig (2010)

Journal of the European Mathematical Society

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We study the enumerative geometry of the moduli space $ℛ_{g}$ of Prym varieties of dimension $g - 1$ . Our main result is that the compactication of $ℛ_{g}$ is of general type as soon as $g > 13$ and $g$ is different from 15. We achieve this by computing the class of two types of cycles on $ℛ_{g}$ : one defined in terms of Koszul cohomology of Prym curves, the other defined in terms of Raynaud theta divisors associated to certain vector bundles on curves. We formulate a Prym–Green conjecture on syzygies of Prym-canonical...

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...

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 $[H] \in C H^{2} (𝒜_{g})$ 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 $H \subset 𝒜_{5}$ has two components, both unirational, which we describe completely. We then determine the slope of the effective cone of $\bar{𝒜_{5}}$ and show that the component $\bar{N_{0}^{'}}$ of the Andreotti-Mayer...

Moduli of smoothness of functions and their derivatives

Z. Ditzian, S. Tikhonov (2007)

Studia Mathematica

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Relations between moduli of smoothness of the derivatives of a function and those of the function itself are investigated. The results are for $L_{p} (T)$ and $L_{p} [- 1, 1]$ for 0 < p < ∞ using the moduli of smoothness $ω^{r} {(f, t)}_{p}$ and $ω_{φ}^{r} {(f, t)}_{p}$ respectively.

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 $π : Z \to X$ 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...

Varieties of Algebras of Polynomial Growth

Daniela La Mattina (2008)

Bollettino dell'Unione Matematica Italiana

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Let $\mathcal{V}$ be a proper variety of associative algebras over a field $F$ of characteristic zero. It is well-known that $\mathcal{V}$ can have polynomial or exponential growth and here we present some classification results of varieties of polynomial growth. In particular we classify all subvarieties of the varieties of almost polynomial growth, i.e., the subvarieties of $\operatorname{\textbf{var}}(G)$ and $\operatorname{\textbf{var}}(UT_{2})$ , where $G$ is the Grassmann algebra and $UT_{2}$ is the algebra of $2\times 2$ upper triangular matrices.

The KSBA compactification for the moduli space of degree two $K 3$ pairs

Radu Laza (2016)

Journal of the European Mathematical Society

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Inspired by the ideas of the minimal model program, Shepherd-Barron, Kollár, and Alexeev have constructed a geometric compactification for the moduli space of surfaces of log general type. In this paper, we discuss one of the simplest examples that fits into this framework: the case of pairs $(X, H)$ consisting of a degree two $K 3$ surface $X$ and an ample divisor $H$ . Specifically, we construct and describe explicitly a geometric compactification ${\bar{P}}_{2}$ for the moduli of degree two $K 3$ pairs. This compactification...

Finiteness of cominuscule quantum $K$ -theory

Anders S. Buch, Pierre-Emmanuel Chaput, Leonardo C. Mihalcea, Nicolas Perrin (2013)

Annales scientifiques de l'École Normale Supérieure

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The product of two Schubert classes in the quantum $K$ -theory ring of a homogeneous space $X = G / P$ is a formal power series with coefficients in the Grothendieck ring of algebraic vector bundles on $X$ . We show that if $X$ is cominuscule, then this power series has only finitely many non-zero terms. The proof is based on a geometric study of boundary Gromov-Witten varieties in the Kontsevich moduli space, consisting of stable maps to $X$ that take the marked points to general Schubert varieties and...

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 $Z\subset J(C)$ 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...

Bounds on the denominators in the canonical bundle formula

Enrica Floris (2013)

Annales de l’institut Fourier

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In this work we study the moduli part in the canonical bundle formula of an lc-trivial fibration whose general fibre is a rational curve. If $r$ is the Cartier index of the fibre, it was expected that $12 r$ would provide a bound on the denominators of the moduli part. Here we prove that such a bound cannot even be polynomial in $r$ , we provide a bound $N (r)$ and an example where the smallest integer that clears the denominators of the moduli part is $N (r) / r$ . Moreover we prove that even locally the denominators...

Soluble Groups with Many Černikov Quotients

Silvana Franciosi, Francesco de Giovanni (1985)

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

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Si studiano i gruppi risolubili non di Černikov a quozienti propri di Černikov. Nel caso periodico tali gruppi sono tutti e soli i prodotti semidiretti $H\ltimes N$ con $N$ $p$ -gruppo abeliano elementare infinito e $H$ gruppo irriducibile di automorfismi di $N$ che sia infinito e di Černikov. Nel caso non periodico invece si riconduce tale studio a quello dei moduli a quozienti propri artiniani su un gruppo risolubile finito, e si fornisce una caratterizzazione di tali moduli.

Bounded Solutions for Some Dirichlet Problems with $L^{1}(\Omega)$ Data

Tommaso Leonori (2007)

Bollettino dell'Unione Matematica Italiana

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In this paper we prove the existence of a solution for a problem whose model is: $\begin{cases}-\Delta u+\frac{u}{\sigma-|u|}=\gamma|\nabla u|^{2}+f(x)&\text{in% }\Omega\\ u=0&\text{on }\partial\Omega\end{cases}$ with $f(x)$ in $L^{1}(\Omega)$ and $\sigma$ , $\gamma>0$ .

Bridgeland-stable moduli spaces for $K$ -trivial surfaces

Daniele Arcara, Aaron Bertram (2013)

Journal of the European Mathematical Society

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We give a one-parameter family of Bridgeland stability conditions on the derived category of a smooth projective complex surface $S$ and describe “wall-crossing behavior” for objects with the same invariants as $𝒪_{C} (H)$ when $H$ generates Pic $(S)$ and $C \in |H|$ . If, in addition, $S$ is a $K 3$ or Abelian surface, we use this description to construct a sequence of fine moduli spaces of Bridgeland-stable objects via Mukai flops and generalized elementary modifications of the universal coherent sheaf. We also discover...

Euler characteristics of moduli spaces of curves

Gilberto Bini, John Harer (2011)

Journal of the European Mathematical Society

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Let $M_{g}^{n}$ be the moduli space of $n$ -pointed Riemann surfaces of genus $g$ . Denote by $\bar{M_{g}^{n}}$ the Deligne-Mumford compactification of $M_{g}^{n}$ . In the present paper, we calculate the orbifold and the ordinary Euler characteristic of $\bar{M_{g}^{n}}$ for any $g$ and $n$ such that $n > 2 - 2 g$ .

Green's generic syzygy conjecture for curves of even genus lying on a K3 surface

Claire Voisin (2002)

Journal of the European Mathematical Society

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We consider the generic Green conjecture on syzygies of a canonical curve, and particularly the following reformulation thereof: For a smooth projective curve $C$ of genus $g$ in characteristic 0, the condition $Cliff C > l$ is equivalent to the fact that $K_{g - l^{'} - 2, 1} (C, K_{C}) = 0, \forall l^{'} \leq l$ . We propose a new approach, which allows up to prove this result for generic curves $C$ of genus $g (C)$ and gonality $gon(C)$ in the range $\frac{g (C)}{3} + 1 \leq gon(C) \leq \frac{g (C)}{2} + 1 .$

Geometry of Syzygies via Poncelet Varieties

Giovanna Ilardi, Paola Supino, Jean Vallès (2009)

Bollettino dell'Unione Matematica Italiana

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We consider the Grassmannian $\mathbb{G}r(k,n)$ of $(k+1)$ -dimensional linear subspaces of $V_{n}=H^{0}(\mathbb{P}^{1},\mathcal{O}_{\mathbb{P}_{1}}(n))$ . We define $\mathfrak{X}_{k,r,d}$ as the classifying space of the $k$ -dimensional linear systems of degree $n$ on $\mathbb{P}^{1}$ , whose bases realize a fixed number $r$ of polynomial relations of fixed degree $d$ , say $r$ syzygies of degree $d$ . Firstly, we compute the dimension of $\mathfrak{X}_{k,r,d}$ . In the second part we make a link between $\mathfrak{X}_{k,r,d}$ and the Poncelet varieties. In particular, we prove that the existence of linear syzygies implies the existence of singularities on the...

Sufficient Conditions for Integrability of Distortion Function Kf 1

Costantino Capozzoli (2009)

Bollettino dell'Unione Matematica Italiana

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Assume that $\Omega$ , $\Omega^{\prime}$ are planar domains and $f\colon\Omega\xrightarrow{\text{onto}}\Omega^{\prime}$ is a homeomorphism belonging to Sobolev space $W_{\text{loc}}^{1,1}(\Omega;\mathbb{R}^{2})$ with finite distortion. We prove that if the distortion function $K_{f}$ of $f$ satisfies the condition $\operatorname{dist}_{\text{EXP}}(K_{f},L^{\infty})<1$ , then the distortion function $K_{f^{-1}}$ of $f^{-1}$ belongs to $L^{1}_{\text{loc}}(\Omega^{\prime})$ . We show that this result is sharp in sense that the conclusion fails if $\operatorname{dist}_{\text{EXP}}(K_{f},L^{\infty})=1$ . Moreover, we prove that if the distortion function $K_{f}$ satisfies the condition $\operatorname{dist}_{\text{EXP}}(K_{f},L^{\infty})=\lambda$ for some $\lambda>0$ , then $K_{f^{-1}}$ belongs to $L^{p}_{\text{loc}}(\Omega^{\prime})$ for every $p\in(0,\frac{1}{2\lambda})$ . As special case of this result we show that if...

An Elliptic Problem with a Lower Order Term Having Singular Behaviour

Daniela Giachetti, François Murat (2009)

Bollettino dell'Unione Matematica Italiana

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We prove the existence of distributional solutions to an elliptic problem with a lower order term which depends on the solution $u$ in a singular way and on its gradient $D u$ with quadratic growth. The prototype of the problem under consideration is $\begin{cases}-\Delta u+\lambda u=\pm\frac{|Du|^{2}}{|u|^{k}}+f&\text{in}\,% \Omega,\\ u=0&\text{on}\,\partial\Omega,\end{cases}$ where $\lambda>0$ , $k>0$ ; $f(x)\in L^{\infty}(\Omega)$ , $f(x)\geq 0$ (and so $u\geq 0$ ). If $0<k<1$ , we prove the existence of a solution for both the "+" and the "-" signs, while if $k\geq 1$ , we prove the existence of a solution for the "+" sign only.

Chen–Ruan Cohomology of $ℳ_{1, n}$ and ${\bar{ℳ}}_{1, n}$

Nicola Pagani (2013)

Annales de l’institut Fourier

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In this work we compute the Chen–Ruan cohomology of the moduli spaces of smooth and stable $n$ -pointed curves of genus $1$ . In the first part of the paper we study and describe stack theoretically the twisted sectors of $ℳ_{1, n}$ and ${\bar{ℳ}}_{1, n}$ . In the second part, we study the orbifold intersection theory of ${\bar{ℳ}}_{1, n}$ . We suggest a definition for an orbifold tautological ring in genus $1$ , which is a subring of both the Chen–Ruan cohomology and of the stringy Chow ring.

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 $s_{N} \in Γ (X, L^{N})$ 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...

On Zariski's theorem in positive characteristic

Ilya Tyomkin (2013)

Journal of the European Mathematical Society

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In the current paper we show that the dimension of a family $V$ of irreducible reduced curves in a given ample linear system on a toric surface $S$ over an algebraically closed field is bounded from above by $- K_{S} . C + p_{g} (C) - 1$ , where $C$ denotes a general curve in the family. This result generalizes a famous theorem of Zariski to the case of positive characteristic. We also explore new phenomena that occur in positive characteristic: We show that the equality $𝚍𝚒𝚖 (V) = - K_{S} . C + p_{g} (C) - 1$ does not imply the nodality of $C$ even if $C$ belongs...

On the projective genus of surfaces

Pietro Sabatino (2006)

Bollettino dell'Unione Matematica Italiana

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Let $X\subset\mathbb{P}^{N}$ be a smooth irreducible non degenerate surface over the complex numbers, $N\geq 4$ . We define the projective genus of $X$ , denoted by $PG(X)$ , as the geometric genus of the singular curve of the projection of $X$ from a general linear subspace of codimension four. Denote by $g(X)$ the sectional genus of $X$ . In this paper we conjecture that the only surfaces for which $PG(X)=g(X)-1$ are the del Pezzo surface in $\mathbb{P}^{4}$ , in $\mathbb{P}^{5}$ and a conic bundle of degree 5 in $\mathbb{P}^{4}$ . We prove that for $N\geq 5$ if $PG(X)=g(X)-1+\lambda$ , $\lambda$ a non negative integer, then $g(X)\leq\lambda+1+\alpha$ where...

Non-supersingular hyperelliptic jacobians

Yuri G. Zarhin (2004)

Bulletin de la Société Mathématique de France

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Let $K$ be a field of odd characteristic $p$ , let $f (x)$ be an irreducible separable polynomial of degree $n \geq 5$ with big Galois group (the symmetric group or the alternating group). Let $C$ be the hyperelliptic curve $y^{2} = f (x)$ and $J (C)$ its jacobian. We prove that $J (C)$ does not have nontrivial endomorphisms over an algebraic closure of $K$ if either $n \geq 7$ or $p \neq 3$ .

A Note on the Ground State Solutions for the Nonlinear Schrödinger-Maxwell Equations

A. Azzollini, A. Pomponio (2009)

Bollettino dell'Unione Matematica Italiana

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In this paper we study the nonlinear Schrödinger-Maxwell equations $\begin{cases}-\Delta u+V(x)u+\phi u=|u|^{p-1}u&\text{in}\,\,\mathbb{R}^{3},\\ -\Delta\phi=u^{2}&\text{in}\,\,\mathbb{R}^{3}.\end{cases}$ If $V$ is a positive constant, we prove the existence of a ground state solution $(u,\phi)$ for $2<p<5$ . The non-constant potential case is treated for $3<p<5$ , and $V$ possibly unbounded below.

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.

Birational positivity in dimension $4$

Behrouz Taji (2014)

Annales de l’institut Fourier

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In this paper we prove that for a nonsingular projective variety of dimension at most 4 and with non-negative Kodaira dimension, the Kodaira dimension of coherent subsheaves of $Ω^{p}$ is bounded from above by the Kodaira dimension of the variety. This implies the finiteness of the fundamental group for such an $X$ provided that $X$ has vanishing Kodaira dimension and non-trivial holomorphic Euler characteristic.

On varieties of Hilbert type

Lior Bary-Soroker, Arno Fehm, Sebastian Petersen (2014)

Annales de l’institut Fourier

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A variety $X$ over a field $K$ is of Hilbert type if $X (K)$ is not thin. We prove that if $f : X \to S$ is a dominant morphism of $K$ -varieties and both $S$ and all fibers $f^{- 1} (s)$ , $s \in S (K)$ , are of Hilbert type, then so is $X$ . We apply this to answer a question of Serre on products of varieties and to generalize a result of Colliot-Thélène and Sansuc on algebraic groups.