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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 an $n$-dimensional complex Fano manifolds $(n\geq 3)$. Assume that $X$ contains a divisor $A$, which is isomorphic to a rational homogeneous space with Picard number one, such that the conormal bundle $\mathscr{N}^*_{A/X}$ is…

Algebraic Geometry · Mathematics 2021-07-30 Jie Liu

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

We give an explicit construction of prime Fano threefolds of genus 12 with a $G_m$-action, describe their isomorphism classes and automorphism groups.

Algebraic Geometry · Mathematics 2023-06-22 Alexander Kuznetsov , Yuri Prokhorov

We consider mirror symmetry for Fano manifolds, and describe how one can recover the classification of 3-dimensional Fano manifolds from the study of their mirrors. We sketch a program to classify 4-dimensional Fano manifolds using these…

Algebraic Geometry · Mathematics 2021-06-02 Tom Coates , Alessio Corti , Sergey Galkin , Vasily Golyshev , Alexander Kasprzyk

Fano varieties are 'atomic pieces' of algebraic varieties, the shapes that can be defined by polynomial equations. We describe the role of computation and database methods in the construction and classification of Fano varieties, with an…

Algebraic Geometry · Mathematics 2022-11-21 Gavin Brown , Tom Coates , Alessio Corti , Tom Ducat , Liana Heuberger , Alexander Kasprzyk

Following the work of Altmann and Hausen we give a combinatorial description in terms for smooth Fano threefolds admitting a 2-torus action. We show that a whole variety of properties and invariants can be read off from this description. As…

Algebraic Geometry · Mathematics 2018-10-11 Hendrik Süß

We give examples of Fano varieties $X$ with Picard number 1, which have terminal singularities and admit endomorphisms with degree larger than 1.

Algebraic Geometry · Mathematics 2009-01-14 János Kollár , Chenyang Xu

For a variety $X$, a big $\mathbb{Q}$-divisor $L$ and a closed connected subgroup $G \subset \mathrm{Aut}(X, L)$ we define a $G$-invariant version of the $\delta$-threshold. We prove that for a Fano variety $(X, -K_X)$ and a connected…

Algebraic Geometry · Mathematics 2020-08-27 Aleksei Golota

We classify the non-toric, $\mathbb Q$-factorial, Gorenstein, log terminal Fano threefolds of Picard number one that admit an effective action of a two-dimensional algebraic torus.

Algebraic Geometry · Mathematics 2022-11-17 Andreas Bäuerle , Jürgen Hausen

We prove a type of the Lefschetz hyperplane section theorem on Q-Fano 3-folds with Picard number one and $1/2(1,1,1)$-singularities by using some degeneration method. As a byproduct, we obtain a new example of a Calabi-Yau 3-fold $X$ with…

Algebraic Geometry · Mathematics 2011-08-01 Nam-Hoon Lee

A normal projective variety X is called Fano if a multiple of the anticanonical Weil divisor, -K_X, is an ample Cartier divisor, the index of a Fano variety is the number i(X):=sup{t: -K_X= tH, for some ample Cartier divisor H}. Mukai…

alg-geom · Mathematics 2008-02-03 Massimiliano Mella

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 exhibit several families of Fano threefolds with a multiplicative Chow-K\"unneth decomposition, in the sense of Shen-Vial. As a consequence, a certain tautological subring of the Chow ring of powers of these threefolds injects into…

Algebraic Geometry · Mathematics 2023-01-06 Robert Laterveer

A famous theorem of Shokurov states that a general anticanonical divisor of a smooth Fano threefold is a smooth K3 surface. This is quite surprising since there are several examples where the base locus of the anticanonical system has…

Algebraic Geometry · Mathematics 2025-04-16 Andreas Höring , Saverio Andrea Secci

We study fibers with isolated singularities of Landau-Ginzburg models for Fano threefolds of Picard rank one. We compare the data we get with maximal known lengths of exceptional collections in derived categories of coherent sheaves on the…

Algebraic Geometry · Mathematics 2026-01-26 Victor Przyjalkowski

Let X be a smooth, complex Fano 4-fold, and rho(X) its Picard number. If X contains a prime divisor D with rho(X)-rho(D)>2, then either X is a product of del Pezzo surfaces, or rho(X)=5 or 6. In this setting, we completely classify the case…

Algebraic Geometry · Mathematics 2020-07-23 Cinzia Casagrande , Eleonora A. Romano

We investigate the rationality problem for $\mathbf{Q}$-Fano threefolds of Fano index $\ge 2$.

Algebraic Geometry · Mathematics 2026-01-22 Yuri Prokhorov

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

Algebraic Geometry · Mathematics 2017-08-16 Yuri Prokhorov

There exist exactly 166 4-dimensional reflexive polytopes such that the corresponding 4-dimensional Gorenstein toric Fano varieties have at worst terminal singularities in codimension 3 and their anticanonical divisor is divisible by 2. For…

Algebraic Geometry · Mathematics 2017-08-23 Victor Batyrev , Maximilian Kreuzer