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We completely classify the Q-factorial terminal toric Fano three-folds such that the sum of the squared torus invariant prime divisors is non-negative.

Algebraic Geometry · Mathematics 2023-02-22 Hiroshi Sato , Ryota Sumiyoshi

This paper is devoted to settle two still open problems, connected with the existence of ample and nef divisors on a Q-factorial complete toric variety. The first problem is about the existence of ample divisors when the Picard number is 2:…

Algebraic Geometry · Mathematics 2018-04-16 Michele Rossi , Lea Terracini

We give a geometric description of the positivity of the Frobenius-trace kernel on a $\mathbb{Q}$-factorial projective toric variety. To do so, we define its Frobenius support as well as the notions of $F$-effectiveness for divisors and…

Algebraic Geometry · Mathematics 2025-06-04 Javier Carvajal-Rojas , Emre Alp Özavcı

Although it is well-known that the complex cobordism ring is a polynomial ring $\Omega_{*}^{U}\cong\mathbb{Z}\left[\alpha_{1},\alpha_{2},\ldots\right]$, an explicit description for convenient generators $\alpha_{1},\alpha_{2},\ldots$ has…

Algebraic Topology · Mathematics 2016-07-20 Andrew Wilfong

We consider subtorus actions on divisorial toric varieties. Here divisoriality means that the variety has many Cartier divisors like quasiprojective and smooth ones. We characterize when a subtorus action on such a toric variety admits a…

Algebraic Geometry · Mathematics 2007-05-23 A. A'Campo-Neuen , J. Hausen

We show that the dual of the cone of divisors on a complete Q-factorial toric variety X whose stable base loci have dimension less than k is generated by curves on small modifications that move in families sweeping out the birational…

Algebraic Geometry · Mathematics 2007-06-23 Sam Payne

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 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 show that quotients of smooth projective toric varieties by $\mu_p$ in positive characteristics $p$ are toric varieties.

Algebraic Geometry · Mathematics 2018-09-05 Tadakazu Sawada

We prove that every Q-factorial complete toric variety is a finite quotient of a poly weighted space (PWS), as defined in our previous work arXiv:1501.05244. This generalizes the Batyrev-Cox and Conrads description of a Q-factorial complete…

Algebraic Geometry · Mathematics 2018-05-21 Michele Rossi , Lea Terracini

For every complete toric variety, there exists a projective toric variety which is isomorphic to it in codimension one. In this paper, we show that every smooth non-projective complete toric threefold of Picard number at most five becomes…

Algebraic Geometry · Mathematics 2025-07-15 Osamu Fujino , Hiroshi Sato

We investigate compact projective generators in the category of equivariant $D$-modules on a smooth affine variety. For a reductive group $G$ acting on a smooth affine variety $X$, there is a natural countable set of compact projective…

Representation Theory · Mathematics 2020-10-07 Gwyn Bellamy , Sam Gunningham , Sam Raskin

We study motivic Chern classes of cones. First we show examples of projective cones of smooth curves such that their various $K$-classes (sheaf theoretic, push-forward and motivic) are all different. Then we show connections between the…

Algebraic Geometry · Mathematics 2020-06-22 László M. Fehér

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

We bring examples of toric varieties blown up at a point in the torus that do not have finitely generated Cox rings. These examples are generalizations of previous work where toric surfaces of Picard number 1 were studied. In this article…

Algebraic Geometry · Mathematics 2017-08-31 José Luis González , Kalle Karu

In this work we provide effective bounds and classification results for rational $\QQ$-factorial Fano varieties with a complexity-one torus action and Picard number one depending on the invariants dimension and Picard index. This…

Algebraic Geometry · Mathematics 2012-11-26 Elaine Herppich

By the classical result of Milnor and Novikov, the unitary cobordism ring is isomorphic to a graded polynomial ring with countably many generators: $\Omega^U_*\simeq \mathbb Z[a_1,a_2,\dots]$, ${\rm deg}(a_i)=2i$. In this paper we solve a…

Algebraic Topology · Mathematics 2017-05-23 Yury Ustinovskiy , Grigory Solomadin

In this paper we study the geometry of mildly singular Fano varieties on which there is an effective prime divisor of Picard number one. Afterwards, we address the case of toric varieties. Finally, we treat the lifting of extremal…

Algebraic Geometry · Mathematics 2017-09-07 Pedro Montero

Let T be a torus over an algebraically closed field k of characteristic 0, and consider a projective T-module P(V). We determine when a projective toric subvariety X of P(V) is self-dual, in terms of the configuration of weights of V.

Algebraic Geometry · Mathematics 2014-02-26 Mathias Bourel , Alicia Dickenstein , Alvaro Rittatore

The main result of this paper is a structural theorem for projective Q-factorial toric varieties X in P^N, covered by lines. We prove that there exists a toric fibration f: X -> Z, locally trivial in the Zariski topology, with fiber a…

Algebraic Geometry · Mathematics 2007-05-23 C. Casagrande , S. Di Rocco
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