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We prove that the derived category of a smooth complete intersection variety is equivalent to a full subcategory of the derived category of a smooth projective Fano variety. This enables us to define some new invariants of smooth projective…

Algebraic Geometry · Mathematics 2015-04-30 Young-Hoon Kiem , In-Kyun Kim , Hwayoung Lee , Kyoung-Seog Lee

Let $X$ be a K3 surface with Picard number 1 and genus $g$, such that $g\not\equiv 3 \mod 4$. In this paper, we show that $X$ is a Fano visitor, i.e., there is a smooth Fano variety $Y$ and an embedding $D^b(X)\hookrightarrow D^b(Y)$ given…

Algebraic Geometry · Mathematics 2025-05-08 Anibal Aravena

A classical result of Bondal-Orlov states that a standard flip in birational geometry gives rise to a fully faithful functor between derived categories of coherent sheaves. We complete their embedding into a semiorthogonal decomposition by…

Algebraic Geometry · Mathematics 2023-02-22 Pieter Belmans , Lie Fu , Theo Raedschelders

The purpose of this note is twofold. First, we give a quick proof of Ballico-Chiantini's theorem stating that a Fano or Calabi-Yau variety of dimension at least 4 in codimension two is a complete intersection. Second, we improve Barth-Van…

Algebraic Geometry · Mathematics 2024-05-21 Jinhyung Park

In this article, we introduce a new approach to show the existence and smoothing of simple normal crossing varieties in a given projective space. Our approach relates the above to the existence of nowhere reduced schemes called ribbons and…

Algebraic Geometry · Mathematics 2024-03-08 Purnaprajna Bangere , Francisco Javier Gallego , Jayan Mukherjee

Complete intersections inside rational homogeneous varieties provide interesting examples of Fano manifolds. For example, if $X = \cap_{i=1}^r D_i \subset G/P$ is a general complete intersection of $r$ ample divisors such that $K_{G/P}^*…

Algebraic Geometry · Mathematics 2018-08-07 Chenyu Bai , Baohua Fu , Laurent Manivel

The Debarre-de Jong conjecture predicts that the Fano variety of lines on a smooth Fano hypersurface in $\mathbb{P}^n$ is always of the expected dimension. We generalize this conjecture to the case of Fano complete intersections and prove…

Algebraic Geometry · Mathematics 2020-02-13 Samir Canning

Fano varieties are subvarieties of the Grassmannian whose points parametrize linear subspaces contained in a given projective variety. These expository notes give an account of results on Fano varieties of complete intersections, with a…

Algebraic Geometry · Mathematics 2012-12-05 Paul Larsen

A V_{12} Fano threefold is a smooth Fano threefold X of index 1 with Pic X = Z and (-K_X)^3=12. We show that the bounded derived category of coherent sheaves on any V_{12} threefold X admits a semiorthogonal decomposition consisting of two…

Algebraic Geometry · Mathematics 2007-05-23 Alexander Kuznetsov

We show that the derived categories of symmetric products of a curve are embedded into the derived categories of the moduli spaces of vector bundles of large ranks on the curve. It supports a prediction of the existence of a semiorthogonal…

Algebraic Geometry · Mathematics 2023-09-28 Kyoung-Seog Lee , Han-Bom Moon

For a smooth curve $B$ over an algebraically closed field $k$, for every $B$-flat complete intersection $X_B$ in $B\times_{\text{Spec}\ k} \mathbb{P}^n_k$ of type $(d_1,\dots,d_c)$, if the Fano index is $\geq 2$ and if…

Algebraic Geometry · Mathematics 2018-12-31 Jason Michael Starr , Zhiyu Tian , Runhong Zong

We study Fano schemes $F_k(X)$ for complete intersections $X$ in a projective toric variety $Y\subset \mathbb{P}^n$. Our strategy is to decompose $F_k(X)$ into closed subschemes based on the irreducible decomposition of $F_k(Y)$ as studied…

Algebraic Geometry · Mathematics 2021-06-22 Nathan Ilten , Tyler L. Kelly

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

We prove that the Fano variety of lines of a generic cubic fourfold containing a plane is isomorphic to a moduli space of twisted stable complexes on a K3 surface. On the other hand, we show that the Fano varieties are always birational to…

Algebraic Geometry · Mathematics 2011-12-26 Emanuele Macri , Paolo Stellari

We study Fano varieties endowed with a faithful action of a symmetric group, as well as analogous results for Calabi--Yau varieties, and log terminal singularities. We show the existence of a constant $m(n)$, so that every symmetric group…

Algebraic Geometry · Mathematics 2025-02-05 Louis Esser , Lena Ji , Joaquín Moraga

We study the Picard variety of the Fano surface of nodal and mildly cuspidal cubic threefolds in arbitrary characteristic by relating divisors on the Fano surface to divisors on the symmetric product of a curve of genus 4.

Algebraic Geometry · Mathematics 2010-10-12 Gerard van der Geer , Alexis Kouvidakis

A projective log variety (X, D) is called "a log Fano manifold" if X is smooth and if D is a reduced simple normal crossing divisor on X with -(K_X+D) ample. The n-dimensional log Fano manifolds (X, D) with nonzero D are classified in this…

Algebraic Geometry · Mathematics 2015-01-14 Kento Fujita

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

We study a particular kind of fiber type contractions between complex, projective, smooth varieties f:X->Y, called Fano conic bundles. This means that X is a Fano variety, and every fiber of f is isomorphic to a plane conic. Denoting by…

Algebraic Geometry · Mathematics 2018-03-15 Eleonora Anna Romano

We prove that if a smooth variety with non-positive canonical class can be embedded into a weighted projective space of dimension $n$ as a well formed complete intersection and it is not an intersection with a linear cone therein, then the…

Algebraic Geometry · Mathematics 2020-08-13 Victor Przyjalkowski , Constantin Shramov
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