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We investigate full strongly exceptional collections on smooth, com- plete toric varieties. We obtain explicit results for a large family of varieties with Picard number three, containing many of the families already known. We also describe…

Algebraic Geometry · Mathematics 2021-04-06 Michal Lason , Mateusz Michalek

We prove that Fano n-folds with nef tangent bundle and Picard number greater than n-5 are rational homogeneous manifolds.

Algebraic Geometry · Mathematics 2015-05-13 Akihiro Kanemitsu

Let $E$ be the Whitney sum of complex line bundles over a topological space $X$. Then, the projectivization $P(E)$ of $E$ is called a \emph{projective bundle} over $X$. If $X$ is a non-singular complete toric variety, so is $P(E)$. In this…

Algebraic Topology · Mathematics 2017-01-10 Suyoung Choi , Seonjeong Park

We show that a nef and big line bundle whose adjoint bundle has non-zero global sections on a nonsingular toric weak Fano 3-fold is normally generated. As a consequence, we see that all ample line bundles on a nonsingular toric weak Fano…

Algebraic Geometry · Mathematics 2013-10-25 Shoetsu Ogata

Resolutions of the diagonal of toric varieties has been an active area of study since Beilinson's celebrated resolution of the diagonal for $\PP^n$ and the disproof of King's conjecture. The author generalized a cellular resolution of the…

Algebraic Geometry · Mathematics 2025-12-16 Reginald Anderson

For a smooth complex projective variety, the rank of the N\'eron-Severi group is bounded by the Hodge number h^{1,1}. Varieties with rk NS = h^{1,1} have interesting properties, but are rather sparse, particularly in dimension 2. We discuss…

Algebraic Geometry · Mathematics 2013-10-29 Arnaud Beauville

Let $X$ be a projective nonsingular toric 3-fold with a surjective torus equivariant morphism onto the projective line. Then we prove that an ample line bundle on $X$ is always normally generated.

Algebraic Geometry · Mathematics 2023-09-21 Shoetsu Ogata

A map Y -> P^n is determined by a line bundle quotient of (O_Y)^{n+1}. In this paper, we generalize this description to the case of maps from Y to an arbitrary smooth toric variety. The data needed to determine such a map consists of a…

alg-geom · Mathematics 2008-02-03 David A. Cox

We give an explicit description of all smooth varieties with a torus action of complexity one having Picard number at most two. As a consequence, we classify in every dimension the smooth (almost) Fano varieties with a torus action of…

Algebraic Geometry · Mathematics 2025-07-08 Anne Fahrner , Juergen Hausen , Michele Nicolussi

We prove that a smooth rationally connected projective threefold of Picard number two is toric if and only if it admits an int-amplified endomorphism. As a corollary, we show that a totally invariant smooth curve of a non-isomorphic…

Algebraic Geometry · Mathematics 2025-06-18 Zelong Chen , Sheng Meng , Guolei Zhong

We show that an equivariant vector bundle on a complete toric variety is nef or ample if and only if its restriction to every invariant curve is nef or ample, respectively. Furthermore, we show that nef toric vector bundles have a…

Algebraic Geometry · Mathematics 2010-07-09 Milena Hering , Mircea Mustata , Sam Payne

We describe smooth projective horospherical varieties with Picard number 1. Moreover we prove that the automorphism group of any such variety acts with at most two orbits and we give a geometric characterisation of non-homogeneous ones.

Algebraic Geometry · Mathematics 2007-05-23 Boris Pasquier

We show that the usual sufficient criterion for a generic hypersurface in a smooth projective manifold to have the same Picard number as the ambient variety can be generalized to hypersurfaces in complete simplicial toric varieties. This…

Algebraic Geometry · Mathematics 2013-05-29 Ugo Bruzzo , Antonella Grassi

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

The cellular resolution of the diagonal given by Bayer-Popescu-Sturmfels for unimodular projective toric varieties yields a full, strong exceptional collection of line bundles on unimodular projective toric surfaces. The…

Algebraic Geometry · Mathematics 2024-05-17 Reginald Anderson

In this paper, we give a method to describe the numerical class of a torus invariant surface on a projective toric manifold. As applications, we can classify toric 2-Fano manifolds of Picard number 2 or of dimension at most 4.

Algebraic Geometry · Mathematics 2011-06-30 Hiroshi Sato

A general problem in complex cobordism theory is to find useful representatives for cobordism classes. One particularly convenient class of complex manifolds consists of smooth projective toric varieties. The bijective correspondence…

Algebraic Topology · Mathematics 2013-12-17 Andrew Wilfong

We show that Fano 4-folds with Picard number 5 have Lefschetz defect 3 if and only if they are toric of combinatorial type K. We also find a characterization for such varieties in terms of Picard number of prime divisors. Moreover, we…

Algebraic Geometry · Mathematics 2020-07-22 Eleonora Anna Romano

We give a combinatorial criterion for the tangent bundle on a smooth toric variety to be stable with respect to a given polarisation in terms of the corresponding lattice polytope. Furthermore, we show that for a smooth toric surface and a…

Algebraic Geometry · Mathematics 2019-10-22 Milena Hering , Benjamin Nill , Hendrik Süß

We develop an intersection theory for a singular hemitian line bundle with positive curvature current on a smooth projective variety and irreducible curves on the variety. And we prove the existence of a natural rational fibration structure…

Algebraic Geometry · Mathematics 2007-05-23 Hajime Tsuji