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Kawamata has shown that the quasi-Albanese map of a quasi-projective variety with log-irregularity equal to the dimension and log-Kodaira dimension 0 is birational. In this note we show that under these hypotheses the quasi-Albanese map is…

Algebraic Geometry · Mathematics 2024-01-22 Margarida Mendes Lopes , Rita Pardini , Sofia Tirabassi

We classify singular fibres of a projective Lagrangian fibration over codimension one points. As an application, we obtain a canonical bundle formula for a projective Lagrangian fibration over a smooth manifold.

Algebraic Geometry · Mathematics 2016-11-28 Daisuke Matsushita

We give a proof of Mukai's Theorem on the existence of certain exceptional vector bundles on prime Fano threefolds. To our knowledge this is the first complete proof in the literature. The result is essential for Mukai's biregular…

Algebraic Geometry · Mathematics 2025-09-26 Arend Bayer , Alexander Kuznetsov , Emanuele Macrì

Let $f:X\to U$ be a projective morphism of normal varieties and $(X,\Delta)$ a dlt pair. We prove that if there is an open set $U^0\subset U$, such that $(X,\Delta)\times_U U^0$ has a good minimal model over $U^0$ and the images of all the…

Algebraic Geometry · Mathematics 2012-06-29 Christopher D. Hacon , Chenyang Xu

In this article, we give the structure of codimension one foliations with canonical singularities and numerically trivial canonical class on varieties with klt singularities. Building on recent works of Spicer, Cascini - Spicer and Spicer -…

Algebraic Geometry · Mathematics 2020-08-07 Stéphane Druel , Wenhao Ou

Let $\pi:X\to Y$ be an $n$-dimensional iterated Kodaira fibration with fiber of genus $g$ and injective monodromy. Llosa Isenrich and Py proved that we can pass to a finite index subgroup of $\pi_1(X)$ to get the base space of an…

Geometric Topology · Mathematics 2021-07-05 Kejia Zhu

We investigate the behaviour of the Oka property with respect to deformations of compact complex manifolds. We show that in a family of compact complex manifolds, the set of Oka fibres corresponds to a G-delta subset of the base. We give a…

Complex Variables · Mathematics 2011-06-28 Finnur Larusson

We show that the number of marked minimal models of an n-dimensional smooth complex projective variety of general type can be bounded in terms of its volume, and, if n=3, also in terms of its Betti numbers. For an n-dimensional projective…

Algebraic Geometry · Mathematics 2020-11-30 Diletta Martinelli , Stefan Schreieder , Luca Tasin

We expand the theory of log canonical $3$-fold complements. We prove that if $X\rightarrow T$ is a $3$-dimensional contraction of log Calabi-Yau type, then we can find $B\geq 0$ on $X$ for which $(X,B)$ is log canonical and $n(K_X+B)\sim_T…

Algebraic Geometry · Mathematics 2022-01-06 Stefano Filipazzi , Joaquín Moraga , Yanning Xu

Our aim in this article is to produce new examples of semistable Lazarsfeld- Mukai bundles on smooth projective surfaces $X$ using the notion of parabolic vector bundles. In particular, we associate natural parabolic structures to any rank…

Algebraic Geometry · Mathematics 2017-11-27 Poornapushkala Narayanan

Let $(X, \Delta)$ be a compact K\"ahler klt pair, where $K_X + \Delta$ is ample or numerically trivial, and $\Delta$ has standard coefficients. We show that if equality holds in the orbifold Miyaoka-Yau inequality for $(X, \Delta)$, then…

Algebraic Geometry · Mathematics 2025-06-30 Benoît Claudon , Patrick Graf , Henri Guenancia

Let W -> X be a real smooth projective 3-fold fibred by rational curves. J. Koll\'ar proved that, if W(R) is orientable, then a connected component N of W(R) is essentially either a Seifert fibred manifold or a connected sum of lens spaces.…

Algebraic Geometry · Mathematics 2025-05-26 Fabrizio Catanese , Frederic Mangolte

By applying the positivity theorem of direct images and a pluricanonical version of the structure theorem on the cohomology jumping loci \`a la Green-Lazarsfeld-Simpson, we show that the klt K\"ahler version of the Iitaka conjecture…

Algebraic Geometry · Mathematics 2019-07-17 Juanyong Wang

This is the first of a series of papers, in which we study the plurigenera, the Kodaira dimension and more generally the Iitaka dimension on compact almost complex manifolds. Based on the Hodge theory on almost complex manifolds, we…

Differential Geometry · Mathematics 2020-04-28 Haojie Chen , Weiyi Zhang

We compute the particle spectrum and some of the Yukawa couplings for a family of heterotic compactifications on quintic threefolds X involving bundles that are deformations of TX+O_X. These are then related to the compactifications with…

High Energy Physics - Theory · Physics 2011-11-03 Ron Donagi , Rene Reinbacher , Shing-Tung Yau

It is conjectured that the canonical models of varieties (not of general type) are bounded when the Iitaka volume is fixed. We confirm this conjecture when the general fibers of the corresponding Iitaka fibration are in a fixed bounded…

Algebraic Geometry · Mathematics 2025-09-17 Junpeng Jiao

Let $X$ be an $(n+1)$-dimensional manifold, $\Delta$ be a one-dimensional foliation on $X$, and $p: X \to X / \Delta$ be a quotient map. We will say that a leaf $\omega$ of $\Delta$ is special whenever the space of leaves $X / \Delta$ is…

Geometric Topology · Mathematics 2017-10-19 Sergiy Maksymenko , Eugene Polulyakh

We study some special systems of generators on finite groups, introduced in previous work by the first author and called "diagonal double Kodaira structures", in order to investigate non-abelian, finite quotients of the pure braid group on…

Algebraic Geometry · Mathematics 2022-09-07 Francesco Polizzi , Pietro Sabatino

Given a log canonical pair $(X, \Delta)$, we show that $K_X+\Delta$ is nef assuming there is no non-constant map from the affine line with values in the open strata of the stratification induced by the non-klt locus of $(X, \Delta)$. This…

Algebraic Geometry · Mathematics 2021-10-12 Roberto Svaldi

Working with a singular variety X, one is often interested in comparing the set of etale covers of X with that of its smooth locus X_reg. More precisely, one may ask: What are the obstructions to extend finite etale covers of X_reg to all…

Algebraic Geometry · Mathematics 2013-07-24 Daniel Greb , Stefan Kebekus , Thomas Peternell
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