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Related papers: On some Fano--Enriques threefolds

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We prove that all smooth Fano threefolds with Picard rank 2 and degree 28 are K-polystable, except for some explicit cases which we describe. We also give a classification of the normal bundle of a rational normal quartic curve in a smooth…

Algebraic Geometry · Mathematics 2025-07-17 Joseph Malbon

We prove that all general smooth Fano threefolds of Picard rank $3$ and degree $14$ are K-stable, where the generality condition is stated explicitly.

Algebraic Geometry · Mathematics 2024-05-22 Grigory Belousov , Konstantin Loginov

In this paper, we study the linear systems $|-mK_X|$ on Fano varieties $X$ with klt singularities. In a given dimension $d$, we prove $|-mK_X|$ is non-empty and contains an element with "good singularities" for some natural number $m$…

Algebraic Geometry · Mathematics 2019-04-17 Caucher Birkar

Suppose that $X$ is a smooth, projective threefold over $\mathbb C$ and that $\phi : X \to X$ is an automorphism of positive entropy. We show that one of the following must hold, after replacing $\phi$ by an iterate: i) the canonical class…

Algebraic Geometry · Mathematics 2015-05-20 John Lesieutre

The Fano surface $F$ of lines in the cubic threefold $V$ is naturally embedded in the intermediate Jacobian $J(V)$, we call "Fano cycle" the difference $F-F^-$, this is homologous to 0 in $J(V)$. We study the normal function on the moduli…

Algebraic Geometry · Mathematics 2012-01-24 A. Collino , J. C. Naranjo , G. P. Pirola

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

An inductive approach to classifying toric Fano varieties is given. As an application of this technique, we present a classification of the toric Fano threefolds with at worst canonical singularities. Up to isomorphism, there are 674,688…

Algebraic Geometry · Mathematics 2019-08-15 Alexander M. Kasprzyk

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

Algebraic Geometry · Mathematics 2016-01-29 Yuri Prokhorov

We classify the non-toric, $\mathbb{Q}$-factorial, Gorenstein, Fano threefolds of Picard number one with an effective $\mathbb{K}^*$-action and maximal orbit quotient $\mathbb{P}_2$.

Algebraic Geometry · Mathematics 2025-01-22 Marco Ghirlanda

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 a self-contained and simplified proof of Mukai's classification of prime Fano threefolds of index 1 and genus $g \ge 6$ with at most Gorenstein factorial terminal singularities, and of its extension to higher-dimension.

Algebraic Geometry · Mathematics 2025-07-01 Arend Bayer , Alexander Kuznetsov , Emanuele Macrì

We completely classify toric weakened Fano 3-folds, that is, smooth toric weak Fano 3-folds which are not Fano but are deformed to smooth Fano 3-folds. There exist exactly 15 toric weakened Fano 3-folds up to isomorphisms.

Algebraic Geometry · Mathematics 2007-05-23 Hiroshi Sato

We study the symplectic resolution of the Fano variety of lines on some singular cyclic cubic fourfolds, i.e. cubic fourfolds arising as cyclic 3:1 cover of $\mathbb{P}^4$ branched along a cubic threefold. In particular we are interested in…

Algebraic Geometry · Mathematics 2023-12-27 Samuel Boissière , Paola Comparin , Lucas Li Bassi

The elliptic curves on a surface of general type constitute an obstruction for the cotangent sheaf to be ample. In this paper, we give the classification of the configurations of the elliptic curves on the Fano surface of a smooth cubic…

Algebraic Geometry · Mathematics 2010-01-27 Xavier Roulleau

We survey some recent progress in the study of algebraic varieties X with log terminal singularities, especially, the uni-ruledness of the smooth locus X^0 of X, the fundamental group of X^0 and the automorphisms group on (smooth or…

Algebraic Geometry · Mathematics 2018-06-20 J. Keum , D. -Q. Zhang

We generalize the result of Kawamata concerning the strong version of Fujita's freeness conjecture for smooth 3-folds to some singular cases, namely, Gorenstein terminal singularities and quotient singularities of type 1/r(1,1,1) and of…

Algebraic Geometry · Mathematics 2007-05-23 Nobuyuki Kakimi

This paper was written in 1982. Ideas and methods of "Clemens C.H., Griffiths Ph. The intermediate Jacobian of a cubic threefold" are applied to a Fano threefold X of genus 6 -- intersection of Grassmann sixfold with two hyperplanes and a…

Algebraic Geometry · Mathematics 2007-05-23 Dmitry Logachev

We classify Enriques surfaces with smooth K3 cover and finite automorphism group in arbitrary positive characteristic. The classification is the same as over the complex numbers except that some types are missing in small characteristics.…

Algebraic Geometry · Mathematics 2017-04-07 Gebhard Martin

We study congruences of lines $X_\omega$ defined by a sufficiently general choice of an alternating 3-form $\omega$ in $n+1$ dimensions, as Fano manifolds of index $3$ and dimension $n-1$. These congruences include the…

Algebraic Geometry · Mathematics 2017-02-03 Pietro De Poi , Daniele Faenzi , Emilia Mezzetti , Kristian Ranestad

We point out an interesting relation between hypersurface elliptic singularities and log Enriques surfaces: with a few exceptions, every hypersurface elliptic singularity define some klt log Enriques surface $(S,Diff)$. In many cases, the…

Algebraic Geometry · Mathematics 2010-05-11 Yu. Prokhorov