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We prove that smooth Fano 3-folds in the families 2.18 and 3.4 are K-stable.

Algebraic Geometry · Mathematics 2023-04-25 Ivan Cheltsov , Kento Fujita , Takashi Kishimoto , Jihun Park

We describe the automorphism groups of smooth Fano threefolds of rank 2 and degree 28 in the cases where they are finite.

Algebraic Geometry · Mathematics 2024-05-15 Joseph Malbon

We study Fano manifolds $X$ admitting an unsplit dominating family of rational curves and we prove that the Generalized Mukai Conjecture holds if $X$ has pseudoindex $i_X = (\dim X)/3$ or dimension $\dim X=6$. We also show that this…

Algebraic Geometry · Mathematics 2011-12-25 Carla Novelli

The main purpose of this article is to prove that the family of all Fano threefolds with log-terminal singularities with bounded index is bounded.

alg-geom · Mathematics 2008-02-03 A. Borisov

In this article, we prove that any Q-Calabi-Yau 3-fold with only ordinary terminal singularities and any Q-Fano 3-fold of Fano index 1 with only terminal singularities have Q-smoothings.

Algebraic Geometry · Mathematics 2007-05-23 Tatsuhiro Minagawa

We study smoothings of Fano threefolds. We prove that the Picard number remains constant in the case of terminal Gorenstein singularities.

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

Fano surfaces parametrize the lines of smooth cubic threefolds. In this paper, we study their quotients by some of their automorphism sub-groups. We obtain in that way some interesting surfaces of general type.

Algebraic Geometry · Mathematics 2012-02-10 Xavier Roulleau

We classify smooth Fano threefolds that admit degenerations to toric Fano threefolds with ordinary double points.

Algebraic Geometry · Mathematics 2018-09-11 Sergey Galkin

The Manin-Peyre conjecture is established for smooth spherical Fano threefolds of semisimple rank one and type N. Together with the previously solved case T and the toric cases, this covers all types of smooth spherical Fano threefolds. The…

Number Theory · Mathematics 2024-06-14 Valentin Blomer , Jörg Brüdern , Ulrich Derenthal , Giuliano Gagliardi

Let $\mathcal{X}$ be a smooth Fano threefold over the complex numbers of Picard rank $1$ with finite automorphism group. We give numerical restrictions on the order of the automorphism group $\mathrm{Aut}(\mathcal{X})$ provided the genus…

Algebraic Geometry · Mathematics 2024-08-15 Nikolay Konovalov

Let $X$, $Y$ be Fano threefolds of Picard number one and such that the ample generators of Picard groups are very ample. Let $X$ be of index one and $Y$ be of index two. It is shown that the only morphisms from $X$ to $Y$ are double…

Algebraic Geometry · Mathematics 2007-05-23 Ekaterina Amerik

We prove that all smooth Fano threefolds of rank 4 and degree 24 are K-stable.

Algebraic Geometry · Mathematics 2022-06-27 Grigory Belousov , Konstantin Loginov

We study the moduli spaces of rational curves on prime Fano threefolds of index 1. For general threefolds of most genera we compute the dimension and the number of irreducible components of these moduli spaces. Our results confirm Geometric…

Algebraic Geometry · Mathematics 2019-08-26 Brian Lehmann , Sho Tanimoto

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

By using the classification of Fano 3-folds we prove: Let $X$ be Fano 3-fold. Assume that the tangent bundle $T_X$ of $X$ is not stable (i.e. semi-stable or unstable). Then $b_2\geq 2$ and a relative tangent sheaf $T_{X/Y}$ of a contraction…

alg-geom · Mathematics 2008-02-03 Andreas Steffens

In the present paper we discuss stability of the tanget bundle of a Fano n-fold of index >= n-2 and b_2=1. For example, we prove that all Fano 4-folds with b_2=1 have stable tangent bundle. For this purpose we prove some vanishing theorems…

alg-geom · Mathematics 2008-02-03 Thomas Peternell , Jaroslaw A. Wisniewski

Let $M$ be a smooth Fano threefold such that a canonical extension of the tangent bundle is an affine manifold. We show that $M$ is rational homogeneous.

Algebraic Geometry · Mathematics 2022-11-22 Andreas Höring , Thomas Peternell

Recently, Kanemitsu has discovered a counterexample to the long-standing conjecture that the tangent bundle of a Fano manifold of Picard number one is (semi)stable. His counterexample is a smooth horospherical variety. There is a weaker…

Algebraic Geometry · Mathematics 2021-11-11 Jaehyun Hong

We consider the classification problem of prime $\mathbb{Q}$-Fano 3-folds with at most $1/2(1,1,1)$-singularities, which was initiated in [Taka2]. We construct two distinct classes of such 3-folds with genus one and six…

Algebraic Geometry · Mathematics 2025-11-18 Hiromichi Takagi

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