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Related papers: On toric Fano fibrations

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In this paper we investigate singularities on toric fibrations. In this context we study a conjecture of Shokurov (a special case of which is due to M$^\rm{c}$Kernan) which roughly says that if $(X,B)\to Z$ is an $\epsilon$-lc Fano type log…

Algebraic Geometry · Mathematics 2021-07-07 Caucher Birkar , Yifei Chen

We show the finite generation of certain invariant graded algebras defined on toric weak log Fano fibrations. These are the toric version of FGA algebras, recently introduced by Shokurov in connections to the existence of flips.

Algebraic Geometry · Mathematics 2007-05-23 Florin Ambro

In this note, we reduce various conjectures in birational geometry, including Shokurov conjecture on singularities of the base of log Calabi-Yau fibrations of Fano type and boundedness conjecture for rationally connected Calabi-Yau…

Algebraic Geometry · Mathematics 2026-03-16 Guodu Chen , Chuyu Zhou

In this paper, we investigate singularities on fibrations and related topics. We prove conjectures of McKernan and Shokurov on singularities on Fano type fibrations and a conjecture of the author on singularities on log Calabi-Yau…

Algebraic Geometry · Mathematics 2025-10-07 Caucher Birkar

We study log canonical thresholds (also called global log canonical threshold or $\alpha$-invariant) of $\mathbb{R}$-linear systems. We prove existence of positive lower bounds in different settings, in particular, proving a conjecture of…

Algebraic Geometry · Mathematics 2020-12-02 Caucher Birkar

We prove the existence of good minimal models for any klt algebraically integrable adjoint foliated structure of general type, and that Fano algebraically integrable adjoint foliated structures with total minimal log discrepancies and…

Algebraic Geometry · Mathematics 2025-04-16 Paolo Cascini , Jingjun Han , Jihao Liu , Fanjun Meng , Calum Spicer , Roberto Svaldi , Lingyao Xie

Let $f\colon X\to Z$ be a Mori fibre space. McKernan conjectured that the singularities of $Z$ are bounded in terms of the singularities of $X$. Shokurov generalised this to pairs: let $(X,B)$ be a klt pair and $f\colon X\to Z$ a…

Algebraic Geometry · Mathematics 2012-10-10 Caucher Birkar

Firstly, we see that the bases of the miniversal deformations of isolated $\mathbb{Q}$-Gorenstein toric singularities are quite restricted. In particular, we classify the analytic germs of embedding dimension $\leq 2$ which are the bases of…

Algebraic Geometry · Mathematics 2022-09-13 Andrea Petracci

In this paper, we prove various results on boundedness and singularities of Fano fibrations and of Fano type fibrations. A Fano fibration is a projective morphism $X\to Z$ of algebraic varieties with connected fibres such that $X$ is Fano…

Algebraic Geometry · Mathematics 2022-09-20 Caucher Birkar

In this paper, we prove the canonical bundle formula for Fano type fibrations and Shokurov's conjecture on boundedness of complements for Fano type threefold pairs $(X,B)$ with fibration structures in large characteristics. In particular,…

Algebraic Geometry · Mathematics 2025-11-11 Xintong Jiang

We introduce the concept of topological finite-determinacy for germs of analytic functions within a fixed ideal $I$, which provides a notion of topological finite-determinacy of functions with non-isolated singularities. We prove the…

Algebraic Geometry · Mathematics 2007-05-23 J. Fernandez de Bobadilla

For Fano fibrations with $\epsilon$-lc singularities of a fixed dimension, we show the existence of bounded relative-global complements. If the base of the fibration is of dimension one, we even show the existence of bounded relative-global…

Algebraic Geometry · Mathematics 2024-02-20 Sung Rak Choi , Chuyu Zhou

This survey paper reports on work of Birkar, who confirmed a long-standing conjecture of Alexeev and Borisov-Borisov: Fano varieties with mild singularities form a bounded family once their dimension is fixed. Following Prokhorov-Shramov,…

Algebraic Geometry · Mathematics 2021-02-02 Stefan Kebekus

We prove that iterated toric fibre products from a finite collection of toric varieties are defined by binomials of uniformly bounded degree. This implies that Markov random fields built up from a finite collection of finite graphs have…

Commutative Algebra · Mathematics 2018-02-08 Jan Draisma , Florian M. Oosterhof

We discuss boundedness of toric Fano foliations and connectedness of its dicritical and singular loci. Moreover, we show the set of interpolated $\delta$-lcts for the toric foliations satisfies the descending chain condition.

Algebraic Geometry · Mathematics 2025-02-18 Chih-Wei Chang , Yen-An Chen

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

We prove a conjecture due to V.V. Shokurov on the boundedness of $\epsilon$-log canonical complements on surfaces. As an application we give a new proof to the boundedness of weak log Fano surfaces.

Algebraic Geometry · Mathematics 2007-05-23 Caucher Birkar

We prove the boundedness theorem for Fano threefolds with log-terminal singularities of any fixed index. This is an improvement of our earlier result, where we required additionally that the variety is Q-factorial, with Picard number 1. The…

Algebraic Geometry · Mathematics 2007-05-23 Alexandr Borisov

In this work we use our previous results on the topological classification of generic singular foliation germs on $(\mathbb C^{2},0)$ to construct complete families: after fixing the semi-local topological invariants we prove the existence…

Dynamical Systems · Mathematics 2024-06-07 David Marín , Jean-François Mattei , Eliane Salem

We classify toric Fano threefolds having at worst terminal singularities such that a rank of a $G$-invariant part of a class group equals one, where $G$ is a group acting on the variety by automorphisms.

Algebraic Geometry · Mathematics 2022-09-05 Arman Sarikyan
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