English
Related papers

Related papers: Remarks on defective Fano manifolds

200 papers

Let $X\subset \P^N$ be a nondegenerate irreducible closed subvariety of dimension $n$ over the field of complex numbers and let $SX\subset\P^N$ be its secant variety. $X\subset\P^N$ is called `secant defective' if $\dim(SX)$ is strictly…

Algebraic Geometry · Mathematics 2024-04-30 Kangjin Han

This paper generalizes the first author's preceding works concerning admissible functions on certain Fano manifolds. Here, we study a larger class of functions which can be less symmetric than the ones studied before. When the sup of these…

Differential Geometry · Mathematics 2010-06-09 Adnene Ben Abdesselem , Brahim Dridi

This is a survey article on the existence of locally conformally flat(LCF) and self-dual(SD) metrics on various basic 4-manifolds like simply-connected ones or product types

Differential Geometry · Mathematics 2014-03-18 Mustafa Kalafat

Using the technique of categorical absorption of singularities we prove that the nontrivial components of the derived categories of del Pezzo threefolds of degree $d \in \{2,3,4,5\}$ and crepant categorical resolutions of the nontrivial…

Algebraic Geometry · Mathematics 2024-11-28 Alexander Kuznetsov , Evgeny Shinder

Let X be a Fano manifold of pseudoindex i_X whose Picard number is at least two and let R be an extremal ray of X with exceptional locus Exc(R). We prove an inequality which bounds the length of R in terms of i_X and of the dimension of…

Algebraic Geometry · Mathematics 2007-05-23 Marco Andreatta , Gianluca Occhetta

We exhibit an example of obstructed K-polystable Fano 3-fold $X$ such that the K-moduli stack of K-semistable Fano varieties and the K-moduli space of K-polystable Fano varieties have an embedded point at $[X]$.

Algebraic Geometry · Mathematics 2025-04-03 Andrea Petracci

In this paper we classify rank two Fano bundles $\cE$ on Fano manifolds satisfying $H^2(X,\Z)\cong H^4(X,\Z)\cong\Z$. The classification is obtained via the computation of the nef and pseudoeffective cones of the projectivization…

Algebraic Geometry · Mathematics 2015-03-10 Roberto Muñoz , Gianluca Occhetta , Luis E. Solá Conde

Let $f\colon X\to Y$ be a surjective morphism of Fano manifolds of Picard number 1 whose VMRTs at a general point are not dual defective. Suppose that the tangent bundle $T_X$ is big. We show that $f$ is an isomorphism unless $Y$ is a…

Algebraic Geometry · Mathematics 2024-07-30 Feng Shao , Guolei Zhong

We study Fano threefolds with Picard number one equipped with a holomorphic section in $\Omega_V^1(1)$.

Algebraic Geometry · Mathematics 2007-05-23 Priska Jahnke , Ivo Radloff

We construct first examples of Fano varieties with torsion in their third cohomology group. The examples are constructed as double covers of linear sections of rank loci of symmetric matrices, and can be seen as higher-dimensional analogues…

Algebraic Geometry · Mathematics 2023-11-17 John Christian Ottem , Jørgen Vold Rennemo

Over an algebraically closed field of positive characteristic, we classify smooth Fano threefolds of Picard number one whose anti-canonical linear systems are not very ample. Furthermore, we also prove that an anti-canonically embedded Fano…

Algebraic Geometry · Mathematics 2026-03-13 Hiromu Tanaka

In this notes we classify toric Fano 4-folds having positive second Chern Character.

Algebraic Geometry · Mathematics 2011-09-06 Edilaine Ervilha Nobili

We classify Q-Fano threefolds of Fano index > 2 and big degree.

Algebraic Geometry · Mathematics 2016-01-29 Yuri Prokhorov

We propose an analogue of Dubrovin's conjecture for the case where Fano manifolds have quantum connections of exponential type. It includes the case where the quantum cohomology rings are not necessarily semisimple. The conjecture is…

Algebraic Geometry · Mathematics 2021-01-18 Fumihiko Sanda , Yota Shamoto

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

K{\"u}chle classified the Fano fourfolds that can be obtained as zero loci of global sections of homogeneous vector bundles on Grassmannians. Surprisingly, his classification exhibits two families of fourfolds with the same discrete…

Algebraic Geometry · Mathematics 2015-02-03 Laurent Manivel

We classify rank two vector bundles on a Fano threefold of Picard rank one whose projectivizations are weak Fano. We also prove the existence of examples for each case of the classification result. Our classification includes detailed…

Algebraic Geometry · Mathematics 2025-05-07 Takeru Fukuoka , Wahei Hara , Daizo Ishikawa

In this paper, we study the explicit geometry of threefolds, in particular, Fano varieties. We find an explicitly computable positive integer $N$, such that all but a bounded family of Fano threefolds have $N$-complements. This result has…

Algebraic Geometry · Mathematics 2023-11-14 Caucher Birkar , Jihao Liu

Following previous work by A. Kuznetsov, we study the Fano manifolds obtained as linear sections of the spinor tenfold in $\mathbb{P}^{15}$. Up to codimension three there are finitely many such sections, up to projective equivalence. In…

Algebraic Geometry · Mathematics 2025-05-01 Yingqi Liu , Laurent Manivel

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