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We prove that any Fano manifold of coindex three admitting nef tangent bundle is homogeneous.

代数几何 · 数学 2019-04-24 Kiwamu Watanabe

We show that fixed dimensional klt weak Fano pairs with alpha-invariants and volumes bounded away from $0$ and the coefficients of the boundaries belong to the set of hyperstandard multiplicities $\Phi(\mathscr{R})$ associated to a fixed…

代数几何 · 数学 2018-10-24 Weichung Chen

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

代数几何 · 数学 2016-01-29 Yuri Prokhorov

Let X be a Fano variety of dimension n, pseudoindex i_X and Picard number \rho_X. A generalization of a conjecture of Mukai says that \rho_X(i_X-1)\le n. We prove that the conjecture holds if: a) X has pseudoindex i_X \ge \frac{n+3}{3} and…

代数几何 · 数学 2007-05-23 Marco Andreatta , Elena Chierici , Gianluca Occhetta

Fatighenti and Mongardi have defined Fano varieties of type S6 as zero loci of a certain vector bundle on the Grassmannian $\hbox{Gr}(2,10)$. These varieties have 3 Hodge structures of K3 type in their cohomology. We show that the Chow ring…

代数几何 · 数学 2020-04-28 Robert Laterveer

In our series of papers, we prove that smooth Fano threefolds in positive characteristic lift to the ring of Witt vectors. Moreover, we show that they satisfy Akizuki-Nakano vanishing, $E_1$-degeneration of the Hodge to de Rham spectral…

代数几何 · 数学 2025-05-12 Tatsuro Kawakami , Hiromu Tanaka

We construct examples showing that Stein degree of vertical divisors on non-Fano type log Calabi-Yau fibrations is unbounded.

代数几何 · 数学 2026-02-09 Caucher Birkar , Santai Qu

We refine the classification of weak Fano threefolds with sextic del Pezzo fibrations by considering the Hodge numbers of them. By the refined classification result, such threefolds are classified into 17 cases. The main result of this…

代数几何 · 数学 2019-03-19 Takeru Fukuoka

In this short note we give a characterization of smooth projective varieties of Picard number one that are separably uniruled but not separably rationally connected. We also give a sufficient condition involving the torsion order and the…

代数几何 · 数学 2019-07-17 Jason Michael Starr , Zhiyu Tian

We show that if a link L with non-zero Alexander polynomial admits a locally flat cobordism to a `weakly m-split link', then the cobordism must have genus at least (m-1)/2. This generalises a recent result of J. Pardon.

几何拓扑 · 数学 2012-10-10 Stefan Friedl , Mark Powell

In this paper we classify mildly singular Fano varieties with maximal Picard number whose effective divisors are numerically eventually free.

代数几何 · 数学 2014-11-20 Stéphane Druel

We classify primitive Fano threefolds in positive characteristic whose Picard numbers are at least two. We also classify Fano theefolds of Picard rank two.

代数几何 · 数学 2025-07-24 Masaya Asai , Hiromu Tanaka

We obtain 866 isomorphism classes of five-dimensional nonsingular toric Fano varieties using a computer program and the database of four-dimensional reflexive polytopes. The algorithm is based on the existence of facets of Fano polytopes…

代数几何 · 数学 2010-02-14 Maximilian Kreuzer , Benjamin Nill

In this paper, we study the structure of Fano fibrations of varieties admitting an int-amplified endomorphism. We prove that if a normal $\mathbb{Q}$-factorial klt projective variety $X$ has an int-amplified endomorphism, then there exists…

代数几何 · 数学 2020-02-05 Shou Yoshikawa

We prove that the Fano variety of lines of a cuspidal cyclic cubic fourfold is a symplectic variety with transversal A2-singularities and we study the properties of the nonsymplectic order three automorphism induced by the covering…

代数几何 · 数学 2023-03-28 Samuel Boissiere , Tobias Heckel , Alessandra Sarti

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

代数几何 · 数学 2017-09-29 Carla Novelli , Gianluca Occhetta

We show that the link cobordism maps defined by the author are graded and satisfy a grading change formula. Using the grading change formula, we prove a new bound for $\Upsilon_K(t)$ for knot cobordisms in negative definite 4-manifolds. As…

几何拓扑 · 数学 2018-10-19 Ian Zemke

We investigate the relationship between the Fano type property on fibers over a Zariski dense subset and the global Fano type property. We establish the invariance of N\'eron-Severi spaces, nef cones, effective cones, movable cones, and…

代数几何 · 数学 2026-01-27 Sung Rak Choi , Zhan Li , Chuyu Zhou

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 · 数学 2008-02-03 A. Borisov

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…

代数几何 · 数学 2023-11-14 Caucher Birkar , Jihao Liu