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We give a criterion for certain generic nondegenerate surfaces in a fake weighted projective $3$-space to have Picard number $>1$. These algebraic surfaces are of general type. We do this by considering degenerations (along an edge),…

Algebraic Geometry · Mathematics 2026-04-29 Julius Giesler

In this brief note, we show that every smooth toric variety over the field of complex numbers is an Oka manifold.

Algebraic Geometry · Mathematics 2013-10-16 Finnur Larusson

Any integral convex polytope $P$ in $\mathbb{R}^N$ provides a $N$-dimensional toric variety $X_P$ and an ample divisor $D_P$ on this variety. This paper gives an explicit construction of the algebraic geometric error-correcting code on…

Algebraic Geometry · Mathematics 2021-02-08 Jade Nardi

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

In this short note, we investigate the existence of orbifold K\"ahler-Einstein metrics on toric varieties. In particular, we show that every $\mathbb{Q}$-factorial normal projective toric variety allows an orbifold K\"ahler-Einstein metric.…

Algebraic Geometry · Mathematics 2022-11-15 Lukas Braun

We completely classify toric weakened Fano 3-folds, that is, smooth toric weak Fano 3-folds which are not Fano but are deformed to smooth Fano 3-folds. There exist exactly 15 toric weakened Fano 3-folds up to isomorphisms.

Algebraic Geometry · Mathematics 2007-05-23 Hiroshi Sato

It is shown that a complex normal projective variety has non-positive Kodaira dimension if it admits a non-isomorphic quasi-polarized endomorphism. The geometric structure of the variety is described by methods of equivariant lifting and…

Algebraic Geometry · Mathematics 2018-09-24 Noboru Nakayama , De-Qi Zhang

A foliation is of toric type when it has a combinatorial reduction of singularities. We show that every toric type foliation on (C3, 0), without saddle-nodes, has invariant surface. We extend the argument of Cano-Cerveau, done for the…

Algebraic Geometry · Mathematics 2020-05-19 Felipe Cano , Beatriz Molina-Samper

In a first result, we describe all finitely generated factorial algebras over an algebraically closed field of characteristic zero that come with an effective multigrading of complexity one by means of generators and relations. This enables…

Algebraic Geometry · Mathematics 2011-04-26 Juergen Hausen , Elaine Herppich , Hendrik Süß

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 show that there is a smooth complex projective variety, of any dimension greater than or equal to two, whose automorphism group is discrete and not finitely generated. Moreover, this variety admits infinitely many real forms which are…

Algebraic Geometry · Mathematics 2019-05-29 Tien-Cuong Dinh , Keiji Oguiso

In this paper, we study derived categories of certain toric varieties with Picard number three that are blowing-up another toric varieties along their torus invariant loci of codimension at most three. We construct strong full exceptional…

Algebraic Geometry · Mathematics 2017-02-17 Wahei Hara

For each nonnegative integer m we show that any closed, oriented topological four-manifold with fundamental group Z_{4m+2} and odd intersection form, with possibly seven exceptions, either admits no smooth structure or admits infinitely…

Geometric Topology · Mathematics 2024-06-14 R. Inanc Baykur , Andras I. Stipsicz , Zoltan Szabo

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 study the equivariant real structures on complex horospherical varieties, generalizing classical results known for toric varieties and flag varieties. In particular, we obtain a necessary and sufficient condition for the existence of…

Algebraic Geometry · Mathematics 2021-03-22 Lucy Moser-Jauslin , Ronan Terpereau , Mikhail Borovoi

We totally classify the projective toric varieties whose canonical divisors are divisible by their dimensions. In Appendix, we show that Reid's toric Mori theory implies Mabuchi's characterization of the projective space for toric…

Algebraic Geometry · Mathematics 2007-05-23 Osamu Fujino

In this paper we illustrate an algorithmic procedure which allows to build projective wonderful models for the complement of a toric arrangement in a n-dimensional algebraic torus T. The main step of the construction is a combinatorial…

Algebraic Geometry · Mathematics 2016-09-01 Corrado De Concini , Giovanni Gaiffi

This paper is devoted to extend some Hu-Keel results on Mori dream spaces (MDS) beyond the projective setup. Namely, $\Q$-factorial algebraic varieties with finitely generated class group and Cox ring, here called \emph{weak} Mori dream…

Algebraic Geometry · Mathematics 2022-05-24 Michele Rossi

We construct a large class of projective threefolds with one node (aka non-degenerate quadratic singularity) such that their small resolutions are not projective.

Algebraic Geometry · Mathematics 2022-01-27 Serge Lvovski

The authors give a complete classification of projective threefolds admitting a holomorphic conformal structure. A Corollary is the complete list of projective threefolds, whose tangent bundle is a symmetric square.

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