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Related papers: Horospherical 2-Fano varieties

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We show that some important classes of weak Fano $3$-folds of Picard rank $2$ do not satisfy Bott vanishing. Using this we show that any smooth projective $3$-fold $X$ of Picard rank $2$ with $-K_X$ nef which is the image of a projective…

Algebraic Geometry · Mathematics 2025-09-05 Supravat Sarkar

We introduce a certain birational invariant of a polarized algebraic variety and use that to obtain upper bounds for the counting functions of rational points on algebraic varieties. Using our theorem, we obtain new upper bounds of Manin…

Number Theory · Mathematics 2020-06-24 Sho Tanimoto

We construct 4 di erent families of smooth Fano fourfolds with Picard rank 1, which contain cylinders, i.e., Zariski open subsets of the form Z x A1, where Z is a quasiprojective variety. The affi ne cones over such a fourfold admit eff…

Algebraic Geometry · Mathematics 2014-06-25 Yuri Prokhorov , Mikhail Zaidenberg

We study singular Fano threefolds of type $V_{22}$.

Algebraic Geometry · Mathematics 2017-08-16 Yuri Prokhorov

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

In this paper we classify varieties of Picard number two having two projective bundle structures of any relative dimension, under the assumption that these structures are mutually uniform. As an application we prove the Campana--Peternell…

Algebraic Geometry · Mathematics 2023-07-04 Gianluca Occhetta , Luis E. Solá Conde , Eleonora A. Romano

We construct a deformation family for each of the 34 Hilbert series of index 2 Fano 3-folds. In 18 cases we construct two different families, distinguished by the topology of their general members.

Algebraic Geometry · Mathematics 2022-12-05 Livia Campo

We describe the geometry of K\"uchle varieties (i.e. Fano 4-folds of index 1 contained in the Grassmannians as zero loci of equivariant vector bundles) with Picard number greater than 1 and the structure of their derived categories.

Algebraic Geometry · Mathematics 2018-09-12 Alexander Kuznetsov

We study Fano manifolds of pseudoindex greater than one and dimension greater than five, which are blow-ups of smooth varieties along smooth centers of dimension equal to the pseudoindex of the manifold. We obtain a classification of the…

Algebraic Geometry · Mathematics 2007-09-21 Elena Chierici , Gianluca Occhetta

We show that a non-toric $\mathbb{Q}$-factorial terminal Fano threefold of Picard rank $1$ and Fano index $13$ is a weighted hypersurface of degree $12$ in $\mathbb{P}(3,4,5,6,7)$.

Algebraic Geometry · Mathematics 2026-01-22 Yuri Prokhorov

Symmetric varieties are normal equivarient open embeddings of symmetric homogeneous spaces, and they are interesting examples of spherical varieties. We prove that all smooth Fano symmetric varieties with Picard number one admit…

Algebraic Geometry · Mathematics 2021-01-08 Jae-Hyouk Lee , Kyeong-Dong Park , Sungmin Yoo

We classify the irreducible components of the space of foliations on Fano 3-folds with rank one Picard group. As a corollary we obtain a classification of holomorphic Poisson structures on the same class of 3-folds.

Algebraic Geometry · Mathematics 2012-12-20 Frank Loray , Jorge Vitorio Pereira , Frederic Touzet

In this paper, we classify codimension one foliations on adjoint varieties with most positive anti-canonical class. We show that on adjoint varieties with Picard number one, these foliations are always induced by a pencil of hyperplane…

Algebraic Geometry · Mathematics 2025-07-31 Crislaine Kuster

In this paper, we investigate when there exists a wild hypersurface bundle over a smooth proper toric variety in positive characteristic. In particular, we determine the possibilities for toric varieties with Picard number at most three or…

Algebraic Geometry · Mathematics 2007-05-23 Hiroshi Sato

We extend the notion of reticular Legendrian unfoldings in order to investigate multi-time bifurcations of wavefronts generated by an r-corner. We give a classification list of generic and stable bifurcations with two time parameter and…

Differential Geometry · Mathematics 2013-08-13 Takaharu Tsukada

We classify Fano fivefolds of index two which are projectivization of rank two vector bundles over four dimensional manifolds.

Algebraic Geometry · Mathematics 2017-09-29 Carla Novelli , Gianluca Occhetta

We prove that a weak Fano manifold has unobstructed deformations. For a general variety, we investigate conditions under which a variety is necessarily obstructed.

Algebraic Geometry · Mathematics 2013-05-23 Taro Sano

We show that $\mathbb{Q}$-Fano varieties of fixed dimension with anti-canonical degrees and alpha-invariants bounded from below form a bounded family. As a corollary, K-semistable $\mathbb{Q}$-Fano varieties of fixed dimension with…

Algebraic Geometry · Mathematics 2021-01-22 Chen Jiang

The aim of this note is to investigate the relation between two types of non-singular projective varieties of Picard rank 2, namely the Projective bundles over Projective spaces and certain Blow-up of Projective spaces.

Algebraic Geometry · Mathematics 2023-03-14 Sergey Galkin , D. S. Nagaraj

We classify all $\mathbb{Q}$-factorial Fano intrinsic quadrics of dimension three and Picard number one having at most canonical singularities.

Algebraic Geometry · Mathematics 2020-05-26 Christoff Hische