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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

We classify the smooth projective symmetric G-varieties with Picard number one (and G semisimple). Moreover we prove a criterion for the smoothness of the simple (normal) symmetric varieties whose closed orbit is complete. In particular we…

Algebraic Geometry · Mathematics 2008-09-26 Alessandro Ruzzi

P-resolutions of two-dimensional, cyclic quotient singularities have been introduced to study deformation theory. Those P-resolutions (as well as the singularities themselves) are toric varieties. In the present paper we give a straight,…

alg-geom · Mathematics 2008-02-03 Klaus Altmann

We generalize classical results about the topology of toric varieties to the case of projective Q-factorial T-varieties of complexity one using the language of divisorial fans. We describe the Hodge-Deligne polynomial in the smooth case,…

Algebraic Geometry · Mathematics 2017-12-07 Antonio Laface , Alvaro Liendo , Joaquín Moraga

The present paper is devoted to generalizing, inside the class of projective toric varieties, the classification [Batyrev91], performed by Batyrev in 1991 for smooth complete toric varieties, to the singular $Q$--factorial case. Moreover,…

Algebraic Geometry · Mathematics 2019-12-20 Michele Rossi , Lea Terracini

Toric quiver varieties (moduli spaces of quiver representations) are studied. Given a quiver and a weight there is an associated quasiprojective toric variety together with a canonical embedding into projective space. It is shown that for a…

Representation Theory · Mathematics 2014-02-21 M. Domokos , Dániel Joó

The main purpose of this notes is to supplement the paper reid, which treated Minimal Model Program (also called Mori's Program) on toric varieties. We calculate lengths of negative extremal rays of toric varieties. As an application, we…

Algebraic Geometry · Mathematics 2007-05-23 Osamu Fujino

We present a counterexample to the conjecture of Bihan, Franz, McCrory, and van Hamel concerning the maximality of toric varieties. There exists a six dimensional projective toric variety X with the sum of the mod 2 Betti numbers of X(R)…

Algebraic Geometry · Mathematics 2007-05-23 Valerie Hower

We describe classes of toric varieties of codimension 2 which are either minimally defined by 3 binomial equations over any algebraically closed field, or are set-theoretic complete intersections in exactly one positive characteristic.

Commutative Algebra · Mathematics 2007-06-28 Margherita Barile

We use a polyhedral criterion for the existence of diagonal splittings to investigate which toric varieties X are diagonally split. Our results are stated in terms of the vector configuration given by primitive generators of the…

Algebraic Geometry · Mathematics 2025-01-07 Jed Chou , Milena Hering , Sam Payne , Rebecca Tramel , Ben Whitney

We examine the integral cohomology rings of certain families of $2n$-dimensional orbifolds $X$ that are equipped with a well-behaved action of the $n$-dimensional real torus. These orbifolds arise from two distinct but closely related…

Algebraic Topology · Mathematics 2018-03-16 Anthony Bahri , Soumen Sarkar , Jongbaek Song

We define phylogenetic projective toric model of a trivalent graph as a generalization of a binary symmetric model of a trivalent phylogenetic tree. Generators of the pro- jective coordinate ring of the models of graphs with one cycle are…

Algebraic Geometry · Mathematics 2010-11-23 Weronika Buczyńska

We compute the divisor class group and the Picard group of projective varieties with Hibi rings as homogeneous coordinate rings. These varieties are precisely the toric varieties associated to order polytopes. We use tools from the theory…

Algebraic Geometry · Mathematics 2015-06-09 Tobias Friedl

In this paper, we describe a way to construct cycles which represent the Todd class of a toric variety. Given a lattice with an inner product we assign a rational number m(s) to each rational polyhedral cone s in the lattice, such that for…

Algebraic Geometry · Mathematics 2007-05-23 James Pommersheim , Hugh Thomas

Koll\'ar gave a series of examples of rational surfaces of Picard number $1$ with ample canonical divisor having cyclic singularities. In this paper, we construct several series of new examples in a geometric way, i.e., by blowing up…

Algebraic Geometry · Mathematics 2010-07-13 DongSeon Hwang , JongHae Keum

We show that the pseudoeffective cone of $k$-cycles on a complete complexity one $T$-variety is rational polyhedral for any $k$, generated by classes of $T$-invariant subvarieties. When $X$ is also rational, we give a presentation of the…

Algebraic Geometry · Mathematics 2019-07-26 Bernt Ivar Utstøl Nødland

Using the language of T-varieties, we study torus invariant curves on a complete normal variety $X$ with an effective codimension-one torus action. In the same way that the $T$-invariant Weil divisors on $X$ are sums of "vertical" divisors…

Algebraic Geometry · Mathematics 2013-07-31 Geoffrey Scott

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 initiate the study of positive-tropical generators as positive analogues of the concept of tropical bases. Applying this to the tropicalization of determinantal varieties, we develop criteria for characterizing their positive part. We…

Combinatorics · Mathematics 2022-05-31 Marie-Charlotte Brandenburg , Georg Loho , Rainer Sinn

For any $n\geq 3$, we explicitly construct smooth projective toric $n$-folds of Picard number $\geq 5$, where any nontrivial nef line bundles are big.

Algebraic Geometry · Mathematics 2008-10-24 Osamu Fujino , Hiroshi Sato