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In this paper we prove birational superrigidity of finite covers of degree $d$ of the $M$-dimensional projective space of index 1, where $d\geqslant 5$ and $M\geqslant 10$, with at most quadratic singularities of rank $\geqslant 7$,…

Algebraic Geometry · Mathematics 2019-01-07 Aleksandr V. Pukhlikov

We prove that in the parameter space of $M$-dimensional Fano complete intersections of index one and codimension two the locus of varieties that are not birationally superrigid has codimension at least $\frac12 (M-9)(M-10)-1$.

Algebraic Geometry · Mathematics 2016-04-05 Daniel Evans , Aleksandr Pukhlikov

We propose a study of the foliations of the projective plane induced by simple derivations of the polynomial ring in two indeterminates over the complex field. These correspond to foliations which have no invariant algebraic curve nor…

Algebraic Geometry · Mathematics 2018-12-17 Gael Cousin , Luis Gustavo Mendes , Ivan Pan

In this paper we describe the birational geometry of Fano double spaces $V\stackrel{\sigma}{\to}{\mathbb P}^{M+1}$ of index 2 and dimension $\geqslant 8$ with at mostquadratic singularities of rank $\geqslant 8$, satisfying certain…

Algebraic Geometry · Mathematics 2019-12-11 Aleksandr V. Pukhlikov

This paper is concerned with a sufficient criterion to guarantee that a given foliation on a normal variety has algebraic and rationally connected leaves. Following ideas from a preprint of Bogomolov-McQuillan and using recent works of…

Algebraic Geometry · Mathematics 2009-09-29 Stefan Kebekus , Luis Sola Conde , Matei Toma

We show boundedness of $3$-folds of $\epsilon$-Fano type with Mori fibration structures. The proof is based on the birational boundedness result in our previous work arXiv:1509.08722 combining with arguments in Kawamata \cite{K} and…

Algebraic Geometry · Mathematics 2020-09-01 Chen Jiang

It is conjectured that the canonical models of varieties (not of general type) are bounded when the Iitaka volume is fixed. We confirm this conjecture when the general fibers of the corresponding Iitaka fibration are in a fixed bounded…

Algebraic Geometry · Mathematics 2025-09-17 Junpeng Jiao

We prove that every non-trivial structure of a rationally connected fibre space (and so every structure of a Mori-Fano fibre space) on a general (in the sense of Zariski topology) hypersurface of degree $M$ in the $(M+1)$-dimensional…

Algebraic Geometry · Mathematics 2013-11-14 Aleksandr Pukhlikov

We prove birational boundedness results on complete intersections with trivial canonical class of base point free divisors in (some version of) Fano varieties. Our results imply in particular that Batyrev-Borisov toric construction produces…

Algebraic Geometry · Mathematics 2014-04-30 Lev A. Borisov , Zhan Li

In this paper, we prove the canonical bundle formula for Fano type fibrations and Shokurov's conjecture on boundedness of complements for Fano type threefold pairs $(X,B)$ with fibration structures in large characteristics. In particular,…

Algebraic Geometry · Mathematics 2025-11-11 Xintong Jiang

In this paper we consider Q-Fano 3-fold weighted complete intersections of codimension 2 in the 85 families listed in the Iano-Fletcher's list and determine which cycle is a maximal center or not. For each maximal center, we construct…

Algebraic Geometry · Mathematics 2014-02-06 Takuzo Okada

In this paper we investigate boundedness and volumes of generalised pairs, and give applications to usual pairs especially to a class of pairs that we call stable log minimal models. Fixing the dimension and a DCC set controlling…

Algebraic Geometry · Mathematics 2021-04-06 Caucher Birkar

We prove that every smooth Fano complete intersection of index $1$ and codimension $r$ in $\mathbb{P}^{n+r}$ is birationally superrigid and K-stable if $n\ge 10r$. We also propose a generalization of Tian's criterion of K-stability and, as…

Algebraic Geometry · Mathematics 2021-02-22 Ziquan Zhuang

We study finite $p$-subgroups of birational automorphism groups. By virtue of boundedness theorem of Fano varieties, we prove that there exists a constant $R(n)$ such that a rationally connected variety of dimension $n$ over an…

Algebraic Geometry · Mathematics 2018-09-26 Jinsong Xu

We prove that for every $\epsilon>0$, there is a birationally super-rigid Fano variety $X$ such that $\frac{1}{2}\leqslant\alpha(X)\leqslant \frac{1}{2}+\epsilon$. Also we show that for every $\epsilon>0$, there is a Fano variety $X$ and a…

Algebraic Geometry · Mathematics 2023-04-25 Ivan Cheltsov , Arman Sarikyan , Ziquan Zhuang

In this paper we study the algebraic ranks of foliations on $\mathbb{Q}$-factorial normal projective varieties. We start by establishing a Kobayashi-Ochiai's theorem for Fano foliations in terms of algebraic rank. We then investigate the…

Algebraic Geometry · Mathematics 2023-08-22 Jie Liu

Let $B$ be a smooth projective curve and let $\pi: \mathcal{X} \to B$ be a smooth integral model of a geometrically integral Fano variety over $K(B)$. Geometric Manin's Conjecture predicts the structure of the irreducible components $M…

Algebraic Geometry · Mathematics 2025-04-01 Brian Lehmann , Eric Riedl , Sho Tanimoto

It is well-known that a nonsingular minimal cubic surface is birationally rigid; the group of its birational selfmaps is generated by biregular selfmaps and birational involutions such that all relations between the latter are implied by…

Algebraic Geometry · Mathematics 2008-04-01 Constantin Shramov

We prove singularity criteria for the $t$-K-stability of adjoint foliated structures. We first show that K-semistability of adjoint foliated structures implies log canonicity by extending Odaka's flag ideal characterisation of the mixed…

Algebraic Geometry · Mathematics 2026-05-28 Theodoros Stylianos Papazachariou

We consider a sequence of $C^2$ (or $C^3$) Anosov maps of the two-dimensional torus that satisfy a common cone condition, and show that if their $C^2$ (respectively, $C^3$) norms are uniformly bounded, then the non-stationary stable…

Dynamical Systems · Mathematics 2025-10-02 Alexandro Luna