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Thurston's fibered face theory allows us to partition the set of pseudo-Anosov mapping classes on different compact oriented surfaces into subclasses with related dynamical behavior. This is done via a correspondence between the rational…

Geometric Topology · Mathematics 2019-09-17 Eriko Hironaka

The symmetric projective varieties of rank one are all smooth and Fano by a classic result of Akhiezer. We classify the locally factorial (respectively smooth) projective symmetric $G$-varieties of rank 2 which are Fano. When $G$ is…

Algebraic Geometry · Mathematics 2010-12-22 Alessandro Ruzzi

We prove that the Klein cubic threefold $F$ is the only smooth cubic threefold which has an automorphism of order 11. We compute the period lattice of the intermediate Jacobian of $F$ and study its Fano surface $S$. We compute also the set…

Algebraic Geometry · Mathematics 2010-01-28 Xavier Roulleau

We describe the automorphism groups of smooth Fano threefolds of rank 2 and degree 28 in the cases where they are finite.

Algebraic Geometry · Mathematics 2024-05-15 Joseph Malbon

In this paper, we provide examples of Sarkisov links of type II between complex projective Fano threefolds $X$ with $\rho(X) = 1$. To show examples of these links, we study smooth weak Fano threefolds with extremal rays of type $E$. We…

Algebraic Geometry · Mathematics 2014-01-07 Joseph W. Cutrone , Nicholas A. Marshburn

We classify three-dimensional nodal Fano varieties that are double covers of smooth quadrics branched over intersections with quartics acted on by finite simple non-abelian groups, and study their rationality.

Algebraic Geometry · Mathematics 2018-08-07 Victor Przyjalkowski , Constantin Shramov

We construct 4 di erent families of smooth Fano fourfolds with Picard rank 1, which contain cylinders, i.e., Zariski open subsets of the form Z x A1, where Z is a quasiprojective variety. The affi ne cones over such a fourfold admit eff…

Algebraic Geometry · Mathematics 2014-06-25 Yuri Prokhorov , Mikhail Zaidenberg

We announce a factorization result for equivariant birational morphisms between toric 4-folds whose source is Fano: such a morphism is always a composite of blow-ups along smooth invariant centers. Moreover, we show with a counterexample…

Algebraic Geometry · Mathematics 2007-05-23 Cinzia Casagrande

We prove that a general rational smooth Fano threefold admits a toric model. More precisely, for a general rational smooth Fano threefold $X$, we show the existence of a boundary divisor $D$ for which $(X,D)\simeq_{\rm cbir}…

Algebraic Geometry · Mathematics 2024-07-15 Konstantin Loginov , Joaquín Moraga , Artem Vasilkov

We classify the d-dimensional simplicial, terminal, and reflexive polytopes with at least 3d-2 vertices. In particular, it turns out that these are all smooth Fano polytopes. This improves on previous results of Casagrande in 2006 and Oebro…

Algebraic Geometry · Mathematics 2015-07-31 Benjamin Assarf , Michael Joswig , Andreas Paffenholz

In this paper we study actions of reductive groups on affine spaces. We prove that there is a fan structure on the space of characters of the group, which parameterizes the possible invariant quotients. In the second half of the paper we…

Algebraic Geometry · Mathematics 2007-05-23 Mihai Halic

Let X be a smooth complex Fano 4-fold. We show that if X has a small elementary contraction, then the Picard number rho(X) of X is at most 12. This result is based on a careful study of the geometry of X, on which we give a lot of…

Algebraic Geometry · Mathematics 2022-05-20 C. Casagrande

We determine the complete list of anticanonically embedded quasi smooth log Fano 3-folds in weighted projective 4-spaces. This implies that the Reid-Fletcher list of 95 types of anticanonically embedded quasi smooth terminal Fano threefolds…

Algebraic Geometry · Mathematics 2007-05-23 Jennifer M. Johnson , János Kollár

In this paper, we prove a special case of Campana--Peternell's conjecture in dimension 4. Specifically, we show that a projective smooth fourfold $X$ with $c^2_1(X)\cdot c_2(X)\neq 0$ and strictly nef anti-canonical divisor $-K_X$ is a Fano…

Algebraic Geometry · Mathematics 2023-05-10 Haidong Liu

We prove that, for a spherical Fano threefold not in the Mori-Mukai family 2-29, and a weight function associated with the action of the connected center of a Levi subgroup of its automorphism group, weighted K-polystability is equivalent…

Algebraic Geometry · Mathematics 2024-11-13 Thibaut Delcroix

In our previous research, we constructed the affine varieties $\Sigma_{\mathbb{A}}^{13}$ and $\Pi_{\mathbb{A}}^{14}$ whose partial projectivizations admit $\mathbb{P}^{2}\times\mathbb{P}^{2}$-fibrations with relative Picard number one. In…

Algebraic Geometry · Mathematics 2025-11-03 Hiromichi Takagi

A new class of 3-manifold invariants is constructed from representations of the category of framed tangles.

Geometric Topology · Mathematics 2016-05-20 Olaf Müller

We prove that the Fano variety of lines of a cuspidal cyclic cubic fourfold is a symplectic variety with transversal A2-singularities and we study the properties of the nonsymplectic order three automorphism induced by the covering…

Algebraic Geometry · Mathematics 2023-03-28 Samuel Boissiere , Tobias Heckel , Alessandra Sarti

We consider mirror symmetry for Fano manifolds, and describe how one can recover the classification of 3-dimensional Fano manifolds from the study of their mirrors. We sketch a program to classify 4-dimensional Fano manifolds using these…

Algebraic Geometry · Mathematics 2021-06-02 Tom Coates , Alessio Corti , Sergey Galkin , Vasily Golyshev , Alexander Kasprzyk

We study unirationality and rationality of Fano threefolds of degree 18 over nonclosed fields.

Algebraic Geometry · Mathematics 2019-10-31 Brendan Hassett , Yuri Tschinkel