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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…

代数几何 · 数学 2007-05-23 Alexander Kuznetsov

We classify complex projective manifolds $X$ for which there exists a point $a$ such that the blow-up of $X$ at $a$ is Fano.

代数几何 · 数学 2007-05-23 L. Bonavero , F. Campana , J. A. Wiśniewski

In this paper we classify n-dimensional Fano manifolds with index >=n-2 and positive second Chern character.

代数几何 · 数学 2012-06-08 Carolina Araujo , Ana-Maria Castravet

As a generalization of the Mukai conjecture, we conjecture that the Fano manifolds $X$ which satisfy the property $\rho_X(r_X-1)\geq\dim X-1$ have very special structure, where $\rho_X$ is the Picard number of $X$ and $r_X$ is the index of…

代数几何 · 数学 2015-04-03 Kento Fujita

We classify smooth Fano manifolds X with the Picard number $\rho_X \geq 3$ such that there exists an extremal ray which has a birational contraction that maps a divisor to a point.

代数几何 · 数学 2012-12-21 Kento Fujita

We define additional gradings on two generalisations of Khovanov homology (one due to the first author, the other due to the second), and use them to define invariants of various kinds of embeddings. These include invariants of links in…

几何拓扑 · 数学 2018-09-07 Vassily Olegovich Manturov , William Rushworth

A new class of 3-manifold invariants is constructed from representations of the category of framed tangles.

几何拓扑 · 数学 2016-05-20 Olaf Müller

Let $X$ be a complex smooth Fano variety of dimension at least four. In this paper, we classify such $X$ when the pseudoindex is at least $n-2$ and the Picard number greater than one. We also discuss the relations between pseudoindex and…

代数几何 · 数学 2024-07-12 Kiwamu Watanabe

Fano varieties are basic building blocks in geometry - they are `atomic pieces' of mathematical shapes. Recent progress in the classification of Fano varieties involves analysing an invariant called the quantum period. This is a sequence of…

代数几何 · 数学 2023-09-12 Tom Coates , Alexander M. Kasprzyk , Sara Veneziale

We prove that a weak Fano manifold has unobstructed deformations. For a general variety, we investigate conditions under which a variety is necessarily obstructed.

代数几何 · 数学 2013-05-23 Taro Sano

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

We study the geometry of the Fano schemes $\mathrm{\textbf{F}}_{k}(\mathrm{SD}_n^r)$ of the projective variety $\mathrm{SD}_n^r$ defined by the $r\times r$ minors of a symmetric $n\times n$ matrix filled with indeterminates. These schemes…

代数几何 · 数学 2023-10-12 Ahmad Mokhtar

Let X be a complex Fano manifold of arbitrary dimension, and D a prime divisor in X. We consider the image H of N_1(D) in N_1(X) under the natural push-forward of 1-cycles. We show that the codimension c of H in N_1(X) is at most 8.…

代数几何 · 数学 2011-12-21 C. Casagrande

Generalizing a question of Mukai, we conjecture that a Fano manifold $X$ with Picard number $\rho_X$ and pseudo-index $\iota_X$ satisfies $\rho_X (\iota_X-1) \le \dim(X)$. We prove this inequality in several situations: $X$ is a Fano…

代数几何 · 数学 2007-05-23 L. Bonavero , C. Casagrande , O. Debarre , S. Druel

We establish some inequalities of Chen's type between certain intrinsic invariants (involving sectional, Ricci and scalar curvatures) and the squared mean curvature of submanifolds tangent to the structure vector fields of a generalized…

微分几何 · 数学 2013-06-10 Luis M. Fernández , Ana M. Fuentes

We introduce a new topological invariant, which is a nonnegative integer, of compact manifolds with boundaries associated with a kind of decomposition of them. Let M and N be m-dimensional compact connected manifolds with boundaries. The…

几何拓扑 · 数学 2013-10-16 Eiji Ogasa

Let $X$ be an $n$-dimensional complex Fano manifolds $(n\geq 3)$. Assume that $X$ contains a divisor $A$, which is isomorphic to a rational homogeneous space with Picard number one, such that the conormal bundle $\mathscr{N}^*_{A/X}$ is…

代数几何 · 数学 2021-07-30 Jie Liu

A normal projective variety X is called Fano if a multiple of the anticanonical Weil divisor, -K_X, is an ample Cartier divisor, the index of a Fano variety is the number i(X):=sup{t: -K_X= tH, for some ample Cartier divisor H}. Mukai…

alg-geom · 数学 2008-02-03 Massimiliano Mella

We consider mirror symmetry for Fano manifolds, and describe how one can recover the classification of 3-dimensional Fano manifolds from the study of their mirrors. We sketch a program to classify 4-dimensional Fano manifolds using these…

代数几何 · 数学 2021-06-02 Tom Coates , Alessio Corti , Sergey Galkin , Vasily Golyshev , Alexander Kasprzyk

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

代数几何 · 数学 2016-01-29 Yuri Prokhorov