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We study the conjecture due to V.\,V. Shokurov on characterization of toric varieties. We also consider one generalization of this conjecture. It is shown that none of the characterizations holds true in dimension $\ge 3$. Some weaker…

Algebraic Geometry · Mathematics 2026-02-12 Ilya Karzhemanov

We prove the factoriality of the following nodal threefolds: a complete intersection of hypersurfaces $F$ and $G\subset\mathbb{P}^{5}$ of degree $n$ and $k$ respectively, where $G$ is smooth, $|\mathrm{Sing}(F\cap…

Algebraic Geometry · Mathematics 2007-05-23 Ivan Cheltsov

We establish a structure theorem for degree three codimension one foliations on projective spaces of dimension $n\ge 3$, extending a result by Loray, Pereira, and Touzet for degree three foliations on $\mathbb P^3$. We show that the space…

Algebraic Geometry · Mathematics 2021-12-13 Raphael Constant da Costa , Ruben Lizarbe , Jorge Vitório Pereira

We prove a conjecture of Shafarevich about universal coverings of projective manifolds provided the fundamental group is residually finite.

Algebraic Geometry · Mathematics 2014-01-21 Robert Treger

In this paper we will investigate the global properties of complete Hilbert manifolds with upper and lower bounded sectional curvature. We shall prove the Focal Index Lemma that we will allow us to extend some classical results of finite…

Differential Geometry · Mathematics 2007-05-23 Leonardo Biliotti

We prove that, under mild restrictions, the space of codimension-one foliations of degree one on a smooth projective complete intersection has two irreducible components of logarithmic type. We also prove that the same conclusion holds for…

Algebraic Geometry · Mathematics 2025-12-03 Mateus Figueira , Crislaine Kuster , Ruben Lizarbe , Alan Muniz

In this paper we establish a relationship between the Milnor number, the $\chi$-number, and the Tjurina number of a foliation with respect to an effective balanced divisor of separatrices. Moreover, using the G\'omez-Mont--Seade--Verjovsky…

Complex Variables · Mathematics 2025-12-29 Arturo Fernández-Pérez , Evelia R. García Barroso , Nancy Saravia-Molina

In this article, we prove the Sarkisov Program for co-rank one foliations with suitable singularities on normal projective threefolds. We also exibit a weaker version of birational super-rigidity between two foliated Mori fiber spaces with…

Algebraic Geometry · Mathematics 2026-04-01 Roktim Mascharak

We show that a general ordinary Gushel-Mukai(GM) threefold $X$ is reconstructed from the Kuznetsov component $\mathcal{K}u(X)$ together with an extra data coming from tautological sub-bundle of Grassmannian $\mathrm{Gr}(2,5)$. We also prove…

Algebraic Geometry · Mathematics 2024-02-26 Augustinas Jacovskis , Xun Lin , Zhiyu Liu , Shizhuo Zhang

We provide a rigorous proof of the Gang-Yonekura formula describing the transformation of the 3D index under Dehn filling a cusp in an orientable 3-manifold. The 3D index, originally introduced by Dimofte, Gaiotto and Gukov, is a physically…

Geometric Topology · Mathematics 2025-12-22 Daniele Celoria , Craig D. Hodgson , J. Hyam Rubinstein

We prove that orientable index one minimal surfaces in spherical space forms with large fundamental group have genus at most two. This confirms a conjecture of R. Schoen for an infinite class of 3-manifolds.

Differential Geometry · Mathematics 2018-12-06 Celso Viana

We give an upper bound for the minimal discrepancies of hypersurface singularities. As an application, we show that Shokurov's conjecture is true for log-terminal threefolds.

alg-geom · Mathematics 2007-05-23 Vladimir Masek

We consider generalizations of Szpiro's classical discriminant conjecture to hyperelliptic curves over a number field $K$, and to smooth, projective and geometrically connected curves $X$ over $K$ of genus at least one. The main results…

Number Theory · Mathematics 2013-10-31 Rafael von Känel

We develop two methods for expressing the global index of the gradient of a 2 variable polynomial function $f$: in terms of the atypical fibres of $f$, and in terms of the clusters of Milnor arcs at infinity. These allow us to derive upper…

Algebraic Geometry · Mathematics 2024-10-30 Gabriel E. Monsalve , Mihai Tibăr

We discuss a conjecture of Shokurov on the semi-ampleness of the moduli part of a general fibration.

Algebraic Geometry · Mathematics 2025-10-01 Stefano Filipazzi , Calum Spicer

For a birational analogue of minimal elliptic surfaces X/Y, the singularities of the fibers define a log structure in codimension one on Y. Via base change, we have a log structure in codimension one on Y', for any birational model Y' of Y.…

Algebraic Geometry · Mathematics 2007-05-23 Florin Ambro

The codimension-three conjecture states that any regular holonomic module extends uniquely beyond an analytic subset with codimension equal to or larger than three. We give a proof of this conjecture.

Algebraic Geometry · Mathematics 2013-07-30 Masaki Kashiwara , Kari Vilonen

We prove the existence of tilting objects on some global quotient stacks. As a consequence we provide further evidence for a conjecture on the Rouquier dimension of derived categories formulated by Orlov.

Algebraic Geometry · Mathematics 2017-04-07 Saša Novaković

A conic bundle is a contraction $X\to Z$ between normal varieties of relative dimension $1$ such that $-K_X$ is relatively ample. We prove a conjecture of Shokurov which predicts that, if $X\to Z$ is a conic bundle such that $X$ has…

Algebraic Geometry · Mathematics 2022-07-12 Jingjun Han , Chen Jiang , Yujie Luo

We study the behavior of the Kodaira dimension of algebraic fiber spaces over threefolds. We prove some cases of the Iitaka Conjecture $C_{n,3}$, including certain situations where the base variety is a Calabi--Yau threefold.

Algebraic Geometry · Mathematics 2026-05-12 Houari Benammar Ammar