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We prove that a Fano variety (with arbitrary singularities) of dimension $n$ in positive characteristic is isomorphic to $\mathbb{P}^n$ if the Seshadri constant of the anti-canonical divisor at some smooth point is greater than $n$ and…

Algebraic Geometry · Mathematics 2020-08-06 Ziquan Zhuang

In this article, we determine the existing condition of cylinders in smooth minimal geometrically rational surfaces over a perfect field. Furthermore, we show that for any birational map between smooth projective surfaces, one contains a…

Algebraic Geometry · Mathematics 2023-04-26 Masatomo Sawahara

We prove birational superrigidity of Fano double hypersurfaces of index one with quadratic and multi-quadratic singularities, satisfying certain regularity conditions, and give an effective explicit lower bound for the codimension of the…

Algebraic Geometry · Mathematics 2018-12-31 Thomas Eckl , Aleksandr Pukhlikov

In this paper, we study the structure of Fano fibrations of varieties admitting an int-amplified endomorphism. We prove that if a normal $\mathbb{Q}$-factorial klt projective variety $X$ has an int-amplified endomorphism, then there exists…

Algebraic Geometry · Mathematics 2020-02-05 Shou Yoshikawa

We establish birational superrigidity for a large class of singular projective Fano hypersurfaces of index one. In the special case of isolated singularities, our result applies for instance to: (1) hypersurfaces with semi-homogeneous…

Algebraic Geometry · Mathematics 2016-04-07 Tommaso de Fernex

We address the following question: When an affine cone over a smooth Fano threefold admits an effective action of the additive group? In this paper we deal with Fano threefolds of index 1 and Picard number 1. Our approach is based on a…

Algebraic Geometry · Mathematics 2011-06-08 Takashi Kishimoto , Yuri Prokhorov , Mikhail Zaidenberg

An almost Fano bundle is a vector bundle on a smooth projective variety that its projectivization is an almost Fano variety. In this paper, we prove that almost Fano bundles exist only on almost Fano manifolds and study rank 2 almost Fano…

Algebraic Geometry · Mathematics 2010-04-21 Kazunori Yasutake

We continue to study birational geometry of Fano fibrations $\pi\colon V\to {\mathbb P}^1$ the fibers of which are Fano double hypersurfaces of index 1. For a majority of families of this type, which do not satisfy the condition of…

Algebraic Geometry · Mathematics 2015-06-26 A. V. Pukhlikov

We classify all 1-nodal degenerations of smooth Fano threefolds with Picard number 1 (both nonfactorial and factorial) and describe their geometry. In particular, we describe a relation between such degenerations and smooth Fano threefolds…

Algebraic Geometry · Mathematics 2024-11-14 Alexander Kuznetsov , Yuri Prokhorov

We consider a smooth projective morphism between smooth complex projective varieties. If the source space is a weak Fano (or Fano) manifold, then so is the target space. Our proof is Hodge theoretic. We do not need mod $p$ reduction…

Algebraic Geometry · Mathematics 2010-05-03 Osamu Fujino , Yoshinori Gongyo

Tilting bundles $\mathcal{T}$ on a weighted projective line $\mathbb{X}$ have been intensively studied by representation theorists since they give rise to a derived equivalence between $\mathbb{X}$ and the finite dimensional algebra End…

Representation Theory · Mathematics 2016-04-22 Daniel Chan

We discuss in this note which K3 surfaces appear as anticanonical divisors in a Fano threefold. We prove in particular that a general K3 surface with given Picard lattice P and polarization class h in P is an anticanonical divisor in a Fano…

Algebraic Geometry · Mathematics 2007-05-23 Arnaud Beauville

Fano surfaces parametrize the lines of smooth cubic threefolds. In this paper, we study their quotients by some of their automorphism sub-groups. We obtain in that way some interesting surfaces of general type.

Algebraic Geometry · Mathematics 2012-02-10 Xavier Roulleau

We solve the infinitesimal Torelli problem for $3$-dimensional quasi-smooth ${\mathbb{Q}}$-Fano hypersurfaces with at worst terminal singularities. We also find infinite chains of double coverings of increasing dimension which alternatively…

Algebraic Geometry · Mathematics 2019-02-15 Enrico Fatighenti , Luca Rizzi , Francesco Zucconi

We classify Fano manifolds X containing a divisor E isomorphic to projective space such that the normal bundle $N_{E/X}$ is strictly negative.

Algebraic Geometry · Mathematics 2007-05-23 Toru Tsukioka

The K-moduli space of Fano varieties has been popular in recent research of algebraic geometry. There has been a lot of progress in dimension 3 and we will try to construct explicitly a compactified K-moduli space for the Fano family 2.24.

Algebraic Geometry · Mathematics 2023-09-29 Dongchen Jiao

We present some applications of the deformation theory of toric Fano varieties to K-(semi/poly)stability of Fano varieties. First, we present two examples of K-polystable toric Fano 3-fold with obstructed deformations. In one case, the…

Algebraic Geometry · Mathematics 2021-09-02 Anne-Sophie Kaloghiros , Andrea Petracci

As a special case of a conjecture by Schwede and Smith, we prove that a smooth complex projective threefold with nef anti-canonical divisor is weak Fano if it is of globally $F$-regular type.

Algebraic Geometry · Mathematics 2024-10-08 Paolo Cascini , Tatsuro Kawakami , Shunsuke Takagi

We prove that a quasi-smooth Fano threefold hypersurface is birationally rigid if and only if it has Fano index one.

Algebraic Geometry · Mathematics 2020-07-29 Hamid Ahmadinezhad , Ivan Cheltsov , Jihun Park

This article describes our invention of a new poetic form based on projective geometry. In doing this we also explore the 'what ifs' in mathematics and poetry which spark the creative processes of poet and mathematician. In other words,…

History and Overview · Mathematics 2026-01-13 Katherine Collins , Siaw-Lynn Ng