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In this paper, we prove that a non-projective compact K\"ahler three-fold with nef anti-canonical bundle is, up to a finite \'etale cover, one of the following: a manifold with vanishing first Chern class; the product of a K3 surface and…

Algebraic Geometry · Mathematics 2025-01-09 Shin-ichi Matsumura , Xiaojun Wu

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

Let X be a simply connected projective manifold with nef anticanonical bundle. We prove that X is a product of a rationally connected manifold and a manifold with trivial canonical bundle. As an application we describe the MRC fibration of…

Algebraic Geometry · Mathematics 2017-06-28 Junyan Cao , Andreas Höring

We introduce an explicit class of tempered Laurent polynomials in the sense of Villegas and Doran--Kerr in $n \leqslant 4$ variables including all Landau--Ginzburg models for smooth Fano threefolds with very ample anticanonical class. We…

Algebraic Geometry · Mathematics 2026-05-26 Mikhail Ovcharenko

A determination of the fixed components, base points and irregularity is made for arbitrary numerically effective divisors on any smooth projective rational surface having an effective anticanonical divisor. All of the results are proven…

alg-geom · Mathematics 2009-09-25 Brian Harbourne

We show that there exists a K-stable smooth Fano threefold of the Picard rank 3, the anti-canonical degree 28 and the third Betti number 2.

Algebraic Geometry · Mathematics 2021-07-13 Kento Fujita

We classify Fano threefolds with only terminal singularities whose canonical class is Cartier and divisible by 2, and satisfying an additional assumption that the $G$-invariant part of the Weil divisor class group is of rank 1 with respect…

Algebraic Geometry · Mathematics 2013-08-06 Yuri Prokhorov

In this note we prove that a four-dimensional compact oriented half-confor\-mally flat Riemannian manifold $M^4$ is topologically $\mathbb{S}^{4}$ or $\mathbb{C}\mathbb{P}^{2},$ provided that the sectional curvatures all lie in the interval…

Differential Geometry · Mathematics 2020-03-17 R. Diógenes , E. Ribeiro , E. Rufino

Motivated by the study of Fano type varieties we define a new class of log pairs that we call asymptotically log Fano varieties and strongly asymptotically log Fano varieties. We study their properties in dimension two under an additional…

Algebraic Geometry · Mathematics 2015-09-17 Ivan A. Cheltsov , Yanir A. Rubinstein

We explicitly construct the smooth toric Fano variety which is isomorphic to the blow-up of the projective space at torus invariant points in codimension one by anti-flips.

Algebraic Geometry · Mathematics 2023-05-17 Hiroshi Sato , Shigehito Tsuzuki

We compute global log canonical thresholds, or equivalently alpha invariants, of birationally rigid orbifold Fano threefolds embedded in weighted projective spaces as codimension two or three. As an important application, we prove that most…

Algebraic Geometry · Mathematics 2016-04-04 In-Kyun Kim , Takuzo Okada , Joonyeong Won

This paper initiates the systematic study of the number of points of bounded height on symmetric squares of weak Fano varieties. We provide a general framework for establishing the point count on $\text{Sym}^2 X$. In the specific case of…

Number Theory · Mathematics 2025-06-10 Francesca Balestrieri , Kevin Destagnol , Julian Lyczak , Jennifer Park , Nick Rome

We investigate the universal cover of projective threefolds whose tangent bundle is a direct sum of subbundles in case the Kodaira dimension is not 1 and 2. We also prove results on Fano manifolds with splitting tangent bundles in any…

Algebraic Geometry · Mathematics 2007-05-23 Frederic Campana , Thomas Peternell

Let $C$ be a smooth projective curve over $\mathbb{C}$ of genus $g(C)\geqslant 3$ (respectively, $g(C)=2$). Fix integers $r,k$ such that $2\leqslant k\leqslant r-2$, (respectively, $3\leqslant k\leqslant r-2$). Let $\mathcal{Q}:={\rm…

Algebraic Geometry · Mathematics 2026-04-01 Chandranandan Gangopadhyay , Ronnie Sebastian

In this paper, we prove a conjecture by T. Suzuki, which says if a smooth Fano manifold satisfies some positivity condition on its Chern character, then it can be covered by rational $N$-folds. We prove this conjecture by using purely…

Algebraic Geometry · Mathematics 2018-05-31 Takahiro Nagaoka

In this paper, we study the positivity property of the tangent bundle $T_X$ of a Fano threefold $X$ with Picard number 2. We determine the bigness of the tangent bundle of the whole 36 deformation types. Our result shows that $T_X$ is big…

Algebraic Geometry · Mathematics 2025-04-30 Hosung Kim , Jeong-Seop Kim , Yongnam Lee

In this article, we investigate Serrano's conjecture for strictly nef divisors on projective bundles over higher dimensional smooth projective varieties.

Algebraic Geometry · Mathematics 2024-05-10 Snehajit Misra

In this paper, we prove the canonical bundle formula for Fano type fibrations and Shokurov's conjecture on boundedness of complements for Fano type threefold pairs $(X,B)$ with fibration structures in large characteristics. In particular,…

Algebraic Geometry · Mathematics 2025-11-11 Xintong Jiang

We show that, unlike del Pezzo surfaces, higher dimensional Fano manifolds do not satisfy in general boundedness properties for their ${\rm CH}_0$ group of $0$-cycles. For example, for quartic threefolds having a point of odd degree, there…

Algebraic Geometry · Mathematics 2025-12-02 Claire Voisin

We prove categorical Torelli theorems for four families of Fano double covers with Picard rank greater than 1. Among these is the family of Verra fourfolds. The other three families manifest as double covers of Fano threefolds, branched in…

Algebraic Geometry · Mathematics 2026-05-18 Augustinas Jacovskis , Reinder Meinsma