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Related papers: Exceptional Collections for Toric Fano Fivefolds

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For a generic anti-canonical hypersurface in each smooth toric Fano 4-fold with rank 2 Picard group, we prove there exist three isolated rational curves in it. Moreover, for all these 4-folds except one, the contractions of generic…

Algebraic Geometry · Mathematics 2010-12-21 Jinxing Xu

Chiriv\`{\i} and Maffei \cite{CM II} have proved that the multiplication of sections of any two ample spherical line bundles on the wonderful symmetric variety $X=\bar{G/H}$ is surjective. We have proved two criterions that allows ourselves…

Algebraic Geometry · Mathematics 2010-05-04 Alessandro Ruzzi

In this paper we study smooth toric Fano varieties using primitive relations and toric Mori theory. We show that for any irreducible invariant divisor D in a toric Fano variety X, we have $0\leq\rho_X-\rho_D\leq 3$, for the difference of…

Algebraic Geometry · Mathematics 2007-05-23 Cinzia Casagrande

Let $X$ be a nonsingular complex projective toric variety. We address the question of semi-stability as well as stability for the tangent bundle $T{X}$. In particular, a complete answer is given when $X$ is a Fano toric variety of dimension…

Algebraic Geometry · Mathematics 2021-12-17 Indranil Biswas , Arijit Dey , Ozhan Genc , Mainak Poddar

In this article, we introduce a new approach to show the existence and smoothing of simple normal crossing varieties in a given projective space. Our approach relates the above to the existence of nowhere reduced schemes called ribbons and…

Algebraic Geometry · Mathematics 2024-03-08 Purnaprajna Bangere , Francisco Javier Gallego , Jayan Mukherjee

We call a sheaf on an algebraic variety immaculate if it lacks any cohomology including the zero-th one, that is, if the derived version of the global section functor vanishes. Such sheaves are the basic tools when building exceptional…

Algebraic Geometry · Mathematics 2018-08-29 Klaus Altmann , Jarosław Buczyński , Lars Kastner , Anna-Lena Winz

In this paper, we advance the classification of toric 2-Fano manifolds by continuing the investigation of the minimal projective bundle dimension $m(X) \in \{1,\dots,\dim(X)\}$ introduced in our previous work. This invariant captures the…

We give a complete answer to the question of (semi)stability of tangent bundle of any nonsingular projective complex toric variety with Picard number 2 by using combinatorial crietrion of (semi)stability of an equivariant sheaf. We also…

Algebraic Geometry · Mathematics 2019-10-31 Jyoti Dasgupta , Arijit Dey , Bivas Khan

We show that some important classes of weak Fano $3$-folds of Picard rank $2$ do not satisfy Bott vanishing. Using this we show that any smooth projective $3$-fold $X$ of Picard rank $2$ with $-K_X$ nef which is the image of a projective…

Algebraic Geometry · Mathematics 2025-09-05 Supravat Sarkar

We prove that smooth Fano 5-folds with nef tangent bundles and Picard numbers greater than one are rational homogeneous manifolds.

Algebraic Geometry · Mathematics 2013-04-10 Kiwamu Watanabe

This note is about cycle-theoretic properties of the Fano variety of lines on a smooth cubic fivefold. The arguments are based on the fact that this Fano variety has finite-dimensional motive. We also present some results concerning Chow…

Algebraic Geometry · Mathematics 2017-06-20 Robert Laterveer

We construct a full, strongly exceptional collection of line bundles on the variety X that is the blow up of the projectivization of the vector bundle O_{P^{n-1}}\oplus O_{P^{n-1}}(b) along a linear space of dimension n-2, where b is a…

Algebraic Geometry · Mathematics 2010-02-19 Arijit Dey , Michal Lason , Mateusz Michalek

We construct a full strong exceptional collection consisting of line bundles on any two-dimensional smooth toric weak Fano stack. The total endomorphism algebra of the resulting collection is isomorphic to the path algebra of a quiver with…

Algebraic Geometry · Mathematics 2011-05-31 Akira Ishii , Kazushi Ueda

Let $(X, A)$ be a nonsingular polarized toric 3-fold. We show that if the adjoint bundle of $A$ has no glabal section, then all ample line bundles on $X$ are normally generated. Even if the adjoint bundle is effective, if it is not big,…

Algebraic Geometry · Mathematics 2014-04-29 Shoetsu Ogata

We prove the Yau-Tian-Donaldson's conjecture for any $\mathbb{Q}$-Fano variety that has a log smooth resolution of singularities such that the discrepancies of all exceptional divisors are non-positive. In other words, if such a Fano…

Differential Geometry · Mathematics 2021-03-30 Chi Li , Gang Tian , Feng Wang

We analyze heterotic line bundle models on elliptically fibered Calabi-Yau three-folds over weak Fano bases. In order to facilitate Wilson line breaking to the standard model group, we focus on elliptically fibered three-folds with a second…

High Energy Physics - Theory · Physics 2018-05-09 Andreas P. Braun , Callum R. Brodie , Andre Lukas

We show that a strong version of the geometric Merkurjev-Panin conjecture holds for the Cox category of a projective toric variety. That is, we prove that the full strong exceptional collection of Bondal-Thomsen line bundles is invariant…

Algebraic Geometry · Mathematics 2025-12-23 Daniel Erman , Andrew Hanlon , Gaku Liu , Hailun Zheng

We study the bounded derived categories of torus-equivariant coherent sheaves on smooth toric varieties and Deligne-Mumford stacks. We construct and describe full exceptional collections in these categories. We also observe that these…

Algebraic Geometry · Mathematics 2020-01-08 Lev Borisov , Dmitri Orlov

We find a characterization for Fano 4-folds $X$ with Lefschetz defect $\delta_{X}=3$: besides the product of two del Pezzo surfaces, they correspond to varieties admitting a conic bundle structure $f\colon X\to Y$ with…

Algebraic Geometry · Mathematics 2019-06-26 Pedro Montero , Eleonora Anna Romano

For a Fano threefold admitting a full exceptional collection of vector bundles of length four we show that all full exceptional collections consist of shifted vector bundles. We prove this via a detailed study of the group generated by…

Algebraic Geometry · Mathematics 2026-02-16 Anya Nordskova , Michel Van den Bergh