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In the paper "Birational geometry via moduli spaces" by I. Cheltsov, L. Katzarkov, and V. Przyjalkowski a new structure connecting toric degenerations of smooth Fano threefolds by projections was introduced; using Mirror Symmetry these…

Algebraic Geometry · Mathematics 2019-04-05 Alexander Kasprzyk , Ludmil Katzarkov , Victor Przyjalkowski , Dmitrijs Sakovics

We study the Picard variety of the Fano surface of nodal and mildly cuspidal cubic threefolds in arbitrary characteristic by relating divisors on the Fano surface to divisors on the symmetric product of a curve of genus 4.

Algebraic Geometry · Mathematics 2010-10-12 Gerard van der Geer , Alexis Kouvidakis

We study the deformation theory of a Fano variety X with normal crossing singularities of dimension at most three. We obtain a formula for the sheaf T^1(X) of first order deformations of X in a suitable log resolution of X and its singular…

Algebraic Geometry · Mathematics 2009-07-22 Nikolaos Tziolas

We classify 1-dimensional connected dually flat manifolds $M$ that are toric in the sense of [Molitor, arXiv:2109.04839], and show that the corresponding torifications are complex space forms. Special emphasis is put on the case where M is…

Differential Geometry · Mathematics 2023-09-22 Danuzia Figueirêdo , Mathieu Molitor

We investigate the relationship between the Fano type property on fibers over a Zariski dense subset and the global Fano type property. We establish the invariance of N\'eron-Severi spaces, nef cones, effective cones, movable cones, and…

Algebraic Geometry · Mathematics 2026-01-27 Sung Rak Choi , Zhan Li , Chuyu Zhou

We introduce the notion of a $Y$-pattern with coefficients and its geometric counterpart: a cluster $\mathcal{X}$-variety with coefficients. We use these constructions to build a flat degeneration of every skew-symmetrizable specially…

Algebraic Geometry · Mathematics 2024-09-13 Lara Bossinger , Bosco Frías-Medina , Timothy Magee , Alfredo Nájera Chávez

We classify Q-factorial Gorenstein Fano non-degenerate complete intersection threefolds in fake weighted projective spaces.

Algebraic Geometry · Mathematics 2025-10-14 Juergen Hausen , Paul Weiss

A new class of full fans in an euclidean space - tight fans - is introduced. Such fans are defined using a property of local symmetry in a face of a tiling. Tight fans are related to the theory of parallelotopes in an euclidean space. A…

Metric Geometry · Mathematics 2016-03-08 Andrei Gavrilyuk

Generalising toric geometry we study compact varieties admitting lower dimensional torus actions. In particular we describe divisors on them in terms of convex geometry and give a criterion for their ampleness. These results may be used to…

Algebraic Geometry · Mathematics 2010-12-16 Hendrik Süß

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

We provide an inductive algorithm to compute the bulk-deformed potentials for toric Fano surfaces via wall-crossing techniques and a tropical-holomorphic correspondence theorem for holomorphic discs. As an application of the correspondence…

Symplectic Geometry · Mathematics 2019-02-28 Hansol Hong , Yu-Shen Lin , Jingyu Zhao

We generalize Givental's Theorem for complete intersections in smooth toric varieties in the Fano case. In particular, we find Gromov--Witten invariants of Fano varieties of dimension $\geq 3$, which are complete intersections in weighted…

Algebraic Geometry · Mathematics 2018-08-07 Victor Przyjalkowski

We consider complete toric varieties $X$ such that a maximal unipotent subgroup $U$ of the automorphism group $\text{Aut}(X)$ acts on $X$ with an open orbit. It turns out that such varieties can be characterized by several remarkable…

Algebraic Geometry · Mathematics 2024-04-15 Ivan Arzhantsev , Alexander Perepechko , Kirill Shakhmatov

An inductive approach to classifying toric Fano varieties is given. As an application of this technique, we present a classification of the toric Fano threefolds with at worst canonical singularities. Up to isomorphism, there are 674,688…

Algebraic Geometry · Mathematics 2019-08-15 Alexander M. Kasprzyk

A horospherical variety is a normal algebraic variety where a reductive algebraic group acts with an open orbit which is a torus bundle over a flag variety. For example, toric varieties and flag varieties are horospherical. In this paper,…

Algebraic Geometry · Mathematics 2007-05-23 Boris Pasquier

We state a conjecture on how to construct affine pavings for cohomologically pure projective algebraic varieties, which admit an action of torus such that the fixed points and $1$-dimensional orbits are finite. Experiments on the affine…

Algebraic Geometry · Mathematics 2014-01-10 Zongbin Chen

We introduce the notion of a multi-fan. It is a generalization of that of a fan in the theory of toric variety in algebraic geometry. Roughly speaking a toric variety is an algebraic variety with an action of algebraic torus of the same…

Symplectic Geometry · Mathematics 2007-05-23 Akio Hattori , Mikiya Masuda

The anticanonical complex generalizes the Fano polytope from toric geometry and has been used to study Fano varieties with torus action so far. We work out the case of complete intersections in toric varieties defined by non-degenerate…

Algebraic Geometry · Mathematics 2025-07-01 Juergen Hausen , Christian Mauz , Milena Wrobel

In this paper we show that a smooth toric variety $X$ of Picard number $r\leq 3$ always admits a nef primitive collection supported on a hyperplane admitting non-trivial intersection with the cone $\Nef(X)$ of numerically effective divisors…

Algebraic Geometry · Mathematics 2022-05-24 Michele Rossi , Lea Terracini

We study the extension of a hyperelliptic K3 surface to a Fano 6-fold. This determines a family of surfaces of general type with p_g=1, K^2=2 and hyperelliptic canonical curve, where each surface is a weighted complete intersection inside a…

Algebraic Geometry · Mathematics 2009-10-01 Stephen Coughlan