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Related papers: Conic bundle structures on Q-Fano threefolds

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We classify all Gorenstein Fano threefolds with at worst canonical singularities for which the anticanonical system has a nonempty base locus.

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

We study the spaces of rational curves on Fano threefolds with Gorenstein terminal singularities. We generalize the results regarding Geometric Manin's Conjecture for smooth Fano threefolds, including the classification of subvarieties with…

Algebraic Geometry · Mathematics 2025-05-23 Fumiya Okamura

A Q-conic bundle germ is a proper morphism from a threefold with only terminal singularities to the germ $(Z \ni o)$ of a normal surface such that fibers are connected and the anti-canonical divisor is relatively ample. Building upon our…

Algebraic Geometry · Mathematics 2010-04-26 Shigefumi Mori , Yuri Prokhorov

We construct stable bundle extensions on elliptically fibered Calabi-Yau threefolds. We show that these bundles can solve the topological anomaly constraint in heterotic string theory without the need of invoking background fivebranes.

Algebraic Geometry · Mathematics 2008-11-26 Bjorn Andreas , Gottfried Curio

We survey some results obtained in our quest for Fano varieties of K3 type and discuss why exploring the singular world might be interesting for discovering new K3 structures.

Algebraic Geometry · Mathematics 2025-01-28 Enrico Fatighenti

We give a structure theorem for n-dimensional smooth toric Fano varieties whose associated polytope has "many" pairs of centrally symmetric vertices.

Algebraic Geometry · Mathematics 2007-05-23 Cinzia Casagrande

In this paper we present a construction of stable bundles on Calabi-Yau threefolds using the method of bundle extensions. This construction applies to any given Calabi-Yau threefold with h^{1,1}>1. We give examples of stable bundles of rank…

Algebraic Geometry · Mathematics 2011-11-07 Bjorn Andreas , Norbert Hoffmann

We establish the Hasse principle for $100\%$ of conic bundles over $\mathbb{P}^1_{\mathbb{Q}}$.

Number Theory · Mathematics 2026-04-09 Christopher Frei , Efthymios Sofos

We give the first examples of flat fiber type contractions of Fano manifolds onto varieties that are not weak Fano, and we prove that these morphisms are Fano conic bundles. We also review some known results about the interaction between…

Algebraic Geometry · Mathematics 2017-03-09 Eleonora Anna Romano

We prove that the tangent bundle of a generic space of planar n-gons with specified side lengths, identified under isometry, plus a trivial line bundle is isomorphic to (n-2) times a canonical line bundle. We then discuss consequences for…

Algebraic Topology · Mathematics 2018-05-09 Donald M. Davis

We prove non-rationality and birational super-rigidity of a Q-factorial double cover X of P^3 ramified along a sextic surface with at most simple double points. We also show that the condition #|Sing(X)| < 15 implies Q-factoriality of X. In…

Algebraic Geometry · Mathematics 2007-05-23 Ivan Cheltsov , Jihun Park

We prove that a general rational smooth Fano threefold admits a toric model. More precisely, for a general rational smooth Fano threefold $X$, we show the existence of a boundary divisor $D$ for which $(X,D)\simeq_{\rm cbir}…

Algebraic Geometry · Mathematics 2024-07-15 Konstantin Loginov , Joaquín Moraga , Artem Vasilkov

We prove a homological characterization of $Q$-manifolds bundles over $C$-spaces. This provides a partial answer to Question QM22 from \cite{w}.

Geometric Topology · Mathematics 2020-12-02 V. Valov , J. West

We prove that if there exists a $c_1$-preserving graded ring isomorphism between integral cohomology rings of two Fano Bott manifolds, then they are isomorphic as toric varieties. As a consequence, we give an affirmative answer to McDuff's…

Symplectic Geometry · Mathematics 2020-05-07 Yunhyung Cho , Eunjeong Lee , Mikiya Masuda , Seonjeong Park

A smooth variety is said to satisfy Condition (A) if every finite abelian subgroup of its automorphism group has a fixed point. We classify smooth Fano 3-folds that satisfy Condition (A).

Algebraic Geometry · Mathematics 2025-05-21 Hamid Abban , Ivan Cheltsov , Takashi Kishimoto , Frederic Mangolte

We prove that Kahler-Einstein Fano manifolds with finite automorphism groups form Hausdorff moduli algebraic space with only quotient singularities. We also discuss the limits as Q-Fano varieties which should be put on the boundary of its…

Algebraic Geometry · Mathematics 2014-07-01 Yuji Odaka

Let $X$ be a projective Fano manifold of Picard number one, different from the projective space. There is a folklore conjecture that any non-constant endomorphism of $X$ is an isomorphism. In the first half of this article, we will prove…

Algebraic Geometry · Mathematics 2023-08-08 Sarbeswar Pal

Let $X$ be a smooth Fano manifold equipped with a `` nice '' $n$-blocks collection in the sense of \cite{cm2} and $\mathcal {F}$ a coherent sheaf on $X$. Assume that $X$ is Fano and that all blocks are coherent sheaves. Here we prove that…

Algebraic Geometry · Mathematics 2007-10-23 E. Ballico , F. Malaspina

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

We give conditions for $f$-positivity of relative complete intersections in projective bundles. We also derive an instability result for the fibres.

Algebraic Geometry · Mathematics 2024-07-02 M. A. Barja , L. Stoppino