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We describe a method to construct completions of affine spaces into total spaces of $\mathbb{Q}$-factorial terminal Mori fiber spaces over the projective line. As an application we provide families of examples with non-rational,…

Algebraic Geometry · Mathematics 2021-11-25 Adrien Dubouloz , Takashi Kishimoto , Karol Palka

We prove the following results for projective klt pairs of dimension $3$ over an algebraically closed field of char $p>5$: the cone theorem, the base point free theorem, the contraction theorem, finiteness of minimal models, termination…

Algebraic Geometry · Mathematics 2014-10-17 Caucher Birkar , Joe Waldron

We show that the CM line bundle on a proper family parametrizing specially K-stable varieties with maximal variation is ample. As an application, we show projectivity of any proper subspace of the coarse moduli space of uniformly…

Algebraic Geometry · Mathematics 2023-10-10 Masafumi Hattori

We study Mori fiber spaces over a two-dimensional base which satisfy the semistability assumption. As an application of our technique we give a new proof of the existence of semistable 3-fold flips.

Algebraic Geometry · Mathematics 2015-06-26 Yuri Prokhorov

We settle a question that originates from results and remarks by Koll\'ar on extremal ray in the minimal model program: In positive characteristics, there are no Mori fibrations on threefolds with only terminal singularities whose generic…

Algebraic Geometry · Mathematics 2021-10-04 Andrea Fanelli , Stefan Schröer

We consider $\mathbb{P}(1,1,1,2)$ bundles over $\mathbb{P}^1$ and construct hypersurfaces of these bundles which form a degree 2 del Pezzo fibration over $\mathbb{P}^1$ as a Mori fibre space. We classify all such hypersurfaces whose type…

Algebraic Geometry · Mathematics 2022-07-22 Hamid Abban

We prove that quasi-projective base spaces of smooth families of minimal varieties of general type with maximal variation do not admit Zariski dense entire curves. We deduce the fact that moduli stacks of polarized varieties of this sort…

Algebraic Geometry · Mathematics 2019-12-11 Mihnea Popa , Behrouz Taji , Lei Wu

We consider some conditions under which a smooth projective variety X is actually the projective space. We also extend to the case of positive characteristic some results in the theory of vector bundle adjunction. We use methods and…

Algebraic Geometry · Mathematics 2007-05-23 Marco Andreatta

We show that being a general fibre of a Mori fibre space is a rather restrictive condition for a Fano variety. More specifically, we obtain two criteria (one sufficient and one necessary) for a Q-factorial Fano variety with terminal…

Algebraic Geometry · Mathematics 2016-06-09 Giulio Codogni , Andrea Fanelli , Roberto Svaldi , Luca Tasin

Let k be an algebraically closed field of characteristic zero. Let f:X-->S be a flat, projective morphism of k-schemes of finite type with integral geometric fibers. We prove existence of a projective relative moduli space for semistable…

Algebraic Geometry · Mathematics 2015-03-24 Adrian Langer

Let X be a compact Kaehler threefold such that the base of the MRC-fibration has dimension two. We prove that X is bimeromorphic to a Mori fibre space. Together with our earlier result arXiv:1304.4013 this completes the MMP for compact…

Algebraic Geometry · Mathematics 2017-10-30 Andreas Höring , Thomas Peternell

For good minimal models with klt singularities, polarized by Weil divisors that are relatively nef and big over the bases of the Iitaka fibration, we show that, after fixing appropriate numerical invariants, they form a bounded family. As…

Algebraic Geometry · Mathematics 2025-08-19 Xiaowei Jiang

We study the local structure of Mori contractions $f\colon X\to Z$ of relative dimension one under an additional assumption that there exists a reduced divisor $S$ such that $K_X+S$ is plt and anti-ample.

Algebraic Geometry · Mathematics 2010-05-13 Yuri G. Prokhorov

We study the positivity of CM line bundles on the coarse moduli space of Kawamata log terminal (klt) good minimal models with Kodaira dimension one. We prove that the seminormalization of the moduli space is quasi-projective under a mild…

Algebraic Geometry · Mathematics 2026-01-27 Masafumi Hattori

In this article, we find finitely many numerical invariants to classify the diffeomorphism types of three dimensional simply connected Mori fibre spaces with torsion free homology groups.

Algebraic Geometry · Mathematics 2026-04-28 Feng Hao , Yang Su , Jianqiang Yang

We show that every smooth toric variety (and many other algebraic spaces as well) can be realized as a moduli space for smooth, projective, polarized varieties. Some of these are not quasi--projective. This contradicts a recent paper…

Algebraic Geometry · Mathematics 2007-05-23 János Kollár

We can run the MMP for any divisor on any $\mathbb{Q}$-factorial projective toric variety. We show that two Mori fiber spaces, which are outputs of the above MMP, are connected by finitely many elementary transforms.

Algebraic Geometry · Mathematics 2022-07-14 Keisuke Miyamoto

We show how topology of a space may lead to tensor fields on (the smooth part of) moduli spaces of the fundamental group.

Geometric Topology · Mathematics 2019-01-10 Vladimir Turaev

We suggest to compactify the universal covering of the moduli space of complex structures by non-commutative spaces. The latter are described by certain categories of sheaves with connections which are flat along foliations. In the case of…

Quantum Algebra · Mathematics 2007-05-23 Yan Soibelman

We prove a relative version of the theorem of Cho, Miyaoka and Shepherd-Barron: a Mori fibre space of maximal length is birational to a projective bundle.

Algebraic Geometry · Mathematics 2017-11-27 Andreas Höring , Carla Novelli
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