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Let $V$ be a complex nonsingular projective 3-fold of general type. We shall give a detailed classification up to baskets of singularities on a minimal model of $V$. We show that the $m$-canonical map of $V$ is birational for all $m\geq 73$…

Algebraic Geometry · Mathematics 2010-05-18 Jungkai A. Chen , Meng Chen

The main result of this note is an effective uniform bound for the number of deformation types of certain nonisotrivial families of canonically polarized manifolds. It extends the author's earlier such bound for the classical Shafarevich…

Algebraic Geometry · Mathematics 2010-06-21 Gordon Heier

If $X$ is a smooth complex projective 3-fold with ample canonical divisor $K$, then the inequality $K^3\ge {2/3}(2p_g-7)$ holds, where $p_g$ denotes the geometric genus. This inequality is nearly sharp. We also give similar, but more…

Algebraic Geometry · Mathematics 2007-05-23 Meng Chen

In this paper, we show an extension type theorem for twisted pluricanonical sections on a family of smooth projective manifolds (the twisting line bundle being pseudo-effective and having a prescribed multiplier ideal on the central fiber).

Algebraic Geometry · Mathematics 2016-08-16 Benoît Claudon

This is the third of a series of papers studying real algebraic threefolds, but the methods are mostly independent from the previous two. Let $f:X\to S$ be a map of a smooth projective real algebraic 3-fold to a surface $S$ whose general…

Algebraic Geometry · Mathematics 2007-05-23 János Kollár

We introduce the notion of a simple fibration in $(1,2)$-surfaces. That is, a hypersurface inside a certain weighted projective space bundle over a curve such that the general fibre is a minimal surface of general type with $p_g=2$ and…

Algebraic Geometry · Mathematics 2023-05-05 Stephen Coughlan , Roberto Pignatelli

Let $V$ be a complex nonsingular projective 3-fold of general type. We prove $P_{12}(V)>0$ and $P_{24}(V)>1$ (which answers an open problem of J. Kollar and S. Mori). We also prove that the canonical volume has an universal lower bound…

Algebraic Geometry · Mathematics 2007-10-25 Jungkai A. Chen , Meng Chen

We construct three sequences of regular surfaces of general type with unbounded numerical invariants whose canonical map is 2-to-1 onto a canonically embedded surface. Only sporadic examples of surfaces with these properties were previously…

Algebraic Geometry · Mathematics 2007-05-23 Ciro Ciliberto , Rita Pardini , Francesca Tovena

Any ample Cartier divisor D on a projective variety X is strictly nef (i.e. D.C>0 for any effective curve C on X). In general, the converse statement does not hold. But this is conjectured to be true for anticanonical divisors. The present…

Algebraic Geometry · Mathematics 2016-09-07 H. Uehara

Here we investigate the birational geometry of projective varieties of arbitrary dimension having defective higher secant varieties. We apply the classical tool of tangential projections and we determine natural conditions for uniruledness,…

Algebraic Geometry · Mathematics 2007-05-23 Edoardo Ballico , Claudio Fontanari

We begin a systematic investigation of derived categories of smooth projective toric varieties defined over an arbitrary base field. We show that, in many cases, toric varieties admit full exceptional collections. Examples include all toric…

Algebraic Geometry · Mathematics 2019-08-14 Matthew R. Ballard , Alexander Duncan , Patrick K. McFaddin

We construct canonical heights of subvarieties for dynamical system of several morphisms associated with line bundles defined over a number field, and study some of their properties. We also construct invariant currents for such systems…

Number Theory · Mathematics 2007-05-23 Shu Kawaguchi

We prove a general Zariski-van Kampen-Lefschetz type theorem for higher homotopy groups of generic and nongeneric pencils on singular open complex spaces.

Algebraic Geometry · Mathematics 2016-02-29 Mihai Tibar

This paper studies linear generalised complex structures over vector bundles, as a generalised geometry version of holomorphic vector bundles. In an adapted linear splitting, a linear generalised complex structure on a vector bundle $E\to…

Differential Geometry · Mathematics 2021-05-07 Malte Heuer , Madeleine Jotz Lean

In this note, we investigate fibre space structures of a projective irreducible symplectic manifold. We prove that an 2n-dimensional projective irreducible symplectic manifold admits only an n-dimensional fibration over a Fano variety which…

alg-geom · Mathematics 2016-08-30 Daisuke Matsushita

We contribute to the algebraic-geometric study of discrete integrable systems generated by planar birational maps: (a) we find geometric description of Manin involutions for elliptic pencils consisting of curves of higher degree,…

Exactly Solvable and Integrable Systems · Physics 2023-04-05 Matteo Petrera , Yuri B. Suris , Kangning Wei , Rene Zander

We explore the relation between the positive dimensional irreducible components of the characteristic varieties of rank one local systems on a smooth surface and the associated (rational or irrational) pencils. Our study, which may viewed…

Algebraic Geometry · Mathematics 2010-02-05 Alexandru Dimca

In this thesis we give a complete description of the syzygies of irreducible, nonsingular, canoncial curves $C$ of genus 9. This includes a collection of all possible Betti tables for $C$. Moreover a direct correspondence between these…

Algebraic Geometry · Mathematics 2007-05-23 Michael Sagraloff

We show that certain characteristic varieties of a finitely generated module over a given Weyl algebra arising from weighted degree filtrations are equal to the critical cone of some other characteristic varieties. This behaviour of the…

Rings and Algebras · Mathematics 2011-06-02 Roberto Boldini

Let X ->Y be a Zariski locally trivial fibration of smooth complex projective varieties, with fiber F. We give a structure theorem for the derived category of X provided both F and Z have a full strongly exceptional collection of line…

Algebraic Geometry · Mathematics 2011-02-10 L. Costa , S. Di Rocco , R. M. Miró-Roig