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T.Kishimoto raised the problem to classify all compactifications of contractible affine 3-folds into smooth Fano 3-folds with second Betti number two and classified such compactifications whose log canonical divisors are not nef. In this…

Algebraic Geometry · Mathematics 2017-08-10 Masaru Nagaoka

We develop the quadratic technique of proving birational rigidity of Fano-Mori fibre spaces over a higher-dimensional base. As an application, we prove birational rigidity of generic fibrations into Fano double spaces of dimension…

Algebraic Geometry · Mathematics 2017-12-15 Aleksandr V. Pukhlikov

Given a semistable fibration $f\colon X\to B$ we introduce a correspondence between foliations $\mathcal{F}$ on $X$ and local systems $\mathbb{L}$ on $B$. Building up on this correspondence we find conditions that give maximal rationally…

Algebraic Geometry · Mathematics 2022-05-31 Luca Rizzi , Francesco Zucconi

We show that complex Fano hypersurfaces can have arbitrarily large degrees of irrationality. More precisely, if we fix a Fano index e, then the degree of irrationality of a very general complex Fano hypersurface of index e and dimension n…

Algebraic Geometry · Mathematics 2021-11-11 Nathan Chen , David Stapleton

We investigate the rationality problem for $\mathbf{Q}$-Fano threefolds of Fano index $\ge 2$.

Algebraic Geometry · Mathematics 2026-01-22 Yuri Prokhorov

We investigate in a statistical fashion the smallest height of a rational point on a Fano hypersurface defined over the field of rational numbers. Along the way, we establish an average version of Manin's conjecture about the number of…

Number Theory · Mathematics 2020-06-04 Pierre Le Boudec

This article studies codimension one foliations on projective man-ifolds having a compact leaf (free of singularities). It explores the interplay between Ueda theory (order of flatness of the normal bundle) and the holo-nomy representation…

Classical Analysis and ODEs · Mathematics 2018-08-31 Benoît Claudon , Frank Loray , Jorge Pereira , Frédéric Touzet

In this paper, we address one of the most basic and fundamental problems in the theory of foliations and ODEs, the topological invariance of the algebraic multiplicity of a holomorphic foliation. For instance, we prove an adapted version of…

Complex Variables · Mathematics 2024-11-05 Leonardo M. Câmara , Fernando Reis , José Edson Sampaio

We give a proof by foliation that the cones over $\mathbb{S}^k \times \mathbb{S}^l$ minimize parametric elliptic functionals for each $k,\,l \geq 1$. We also analyze the behavior at infinity of the leaves in the foliations. This analysis…

Analysis of PDEs · Mathematics 2021-04-05 Connor Mooney , Yang Yang

Following T. Suwa, we study unfoldings of algebraic foliations and their relationship with families of foliations, making focus on those unfoldings related to trivial families. The results obtained in the study of unfoldings are then…

Algebraic Geometry · Mathematics 2021-02-09 Federico Quallbrunn

In this paper we study smooth toric Fano varieties using primitive relations and toric Mori theory. We show that for any irreducible invariant divisor D in a toric Fano variety X, we have $0\leq\rho_X-\rho_D\leq 3$, for the difference of…

Algebraic Geometry · Mathematics 2007-05-23 Cinzia Casagrande

We establish a correspondence between simplicial fans, not necessarily rational, and certain foliated compact complex manifolds called LVMB-manifolds. In the rational case, Meersseman and Verjovsky have shown that the leaf space is the…

Complex Variables · Mathematics 2015-03-31 Fiammetta Battaglia , Dan Zaffran

We study holomorphic foliations on normal crossings varieties arising as semistable degenerations. We do so by we exploring the notion of foliated d-semistability using the language of logarithmic structures in the sense of…

Algebraic Geometry · Mathematics 2026-05-04 Mauricio Corrêa , Pablo Perrella , Sebastián Velazquez

We investigate the notion of the $p$-divisor for foliations on a smooth algebraic surface defined over a field of positive characteristic $p$ and we study some of their properties. We present a structure theorem for the $p$-divisor of…

Algebraic Geometry · Mathematics 2022-06-16 Wodson Mendson

We construct $S$-linear semiorthogonal decompositions of derived categories of smooth Fano threefold fibrations $X/S$ with relative Picard rank $1$ and rational geometric fibers and discuss how the structure of components of these…

Algebraic Geometry · Mathematics 2022-10-03 Alexander Kuznetsov

We propose a linear version of the weighted bounded negativity conjecture. It considers a smooth projective surface $X$ over an algebraically closed field of characteristic zero and predicts the existence of a common lower bound on…

Algebraic Geometry · Mathematics 2025-01-27 Carlos Galindo , Francisco Monserrat , Elvira Pérez-Callejo

We investigate Fano varieties defined over a number field that contain subvarieties whose number of rational points of bounded height is comparable to the total number on the variety.

Number Theory · Mathematics 2017-03-23 T. D. Browning , D. Loughran

We describe the algebraic boundaries of the regions of real binary forms with fixed typical rank and of degree at most eight, showing that they are dual varieties of suitable coincident root loci.

Algebraic Geometry · Mathematics 2018-08-28 Maria Chiara Brambilla , Giovanni Staglianò

We find a relation between a cubic hypersurface $Y$ and its Fano variety of lines $F(Y)$ in the Grothendieck ring of varieties. We prove that if the class of an affine line is not a zero-divisor in the Grothendieck ring of varieties, then…

Algebraic Geometry · Mathematics 2014-06-27 Sergey Galkin , Evgeny Shinder

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