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We prove that in the varieties where every compact congruence is a factor congruence and every nontrivial algebra contains a minimal subalgebra, a finitely presented algebra is projective if and only if it has every minimal algebra as its…

Logic · Mathematics 2017-08-11 Alex Citkin

In this paper, we introduce a new homological invariant called quasi-projective dimension, which is a generalization of projective dimension. We discuss various properties of quasi-projective dimension. Among other things, we prove the…

Commutative Algebra · Mathematics 2021-08-18 Mohsen Gheibi , David A. Jorgensen , Ryo Takahashi

This paper generalises Mori's famous theorem about "Projective manifolds with ample tangent bundles" to normal projective varieties in the following way: A normal projective variety over $\mathbb{C}$ with ample tangent sheaf is isomorphic…

Algebraic Geometry · Mathematics 2017-11-15 Philip Sieder

The aim of this article is to prove that, under certain conditions, an affine flat normal scheme that is of finite type over a local Dedekind scheme in mixed characteristic admits infinitely many normal effective Cartier divisors. For the…

Commutative Algebra · Mathematics 2026-03-03 Jun Horiuchi , Kazuma Shimomoto

We show that there are no non-trivial stratified bundles over a smooth simply connected quasi-projective variety over the algebraic closure of a finite field, if the variety admits a normal projective compactification with boundary locus of…

Algebraic Geometry · Mathematics 2019-02-20 Hélène Esnault , Vasudevan Srinivas

We give a generalization of the classical Bombieri--Schneider--Lang criterion in transcendence theory. We give a local notion of $LG$--germ, which is similar to the notion of $E$-- function and Gevrey condition, and which generalize (and…

Algebraic Geometry · Mathematics 2008-11-20 Carlo Gasbarri

We prove under certain conditions that any stable unfolding of a quasi-homogeneous map-germ with finite singularity type is substantial. We then prove that if an equidimensional map-germ is finitely determined, of corank 1, and either it…

Algebraic Geometry · Mathematics 2025-04-09 Ignacio Breva Ribes , Raúl Oset Sinha

The degree of a projective subscheme has an upper bound in term of the codimension and the reduction number. If a projective variety has an almost maximal degree, that is, the degree equals to the upper bound minus one, then its Betti table…

Commutative Algebra · Mathematics 2021-01-19 Doan Trung Cuong , Sijong Kwak

Let $k$ be an algebraically closed field of characteristic zero, and let $X/k$ be a projective variety. The conjectures of Demailly--Green--Griffiths--Lang posit that every integral subvariety of $X$ is of general type if and only if $X$ is…

Algebraic Geometry · Mathematics 2023-06-26 Jackson S. Morrow

This is Part II of a series of three papers. We studies the hyperbolicity of complex quasi-projective varieties $X$ in the presence of a big and reductive representation $\varrho: \pi_1(X)\to {\rm GL}_N(\mathbb{C})$. For any Galois…

Algebraic Geometry · Mathematics 2025-12-18 Benoit Cadorel , Ya Deng , Katsutoshi Yamanoi

We show that the maximum likelihood degree of a smooth very affine variety is equal to the signed topological Euler characteristic. This generalizes Orlik and Terao's solution to Varchenko's conjecture on complements of hyperplane…

Algebraic Geometry · Mathematics 2019-02-20 June Huh

We prove that the multiplication of sections of globally generated line bundles on a model wonderful variety M of simply connected type is always surjective. This follows by a general argument which works for every wonderful variety and…

Algebraic Geometry · Mathematics 2018-06-26 Paolo Bravi , Jacopo Gandini , Andrea Maffei

We prove some results on effective very ampleness and projective normality for some varieties with trivial canonical bundle. In the first part we prove an effective projective normality result for an ample line bundle on regular smooth…

Algebraic Geometry · Mathematics 2019-10-01 Jayan Mukherjee , Debaditya Raychaudhury

We show that local complete intersection subvarieties of smooth projective varieties, which have partially ample normal bundle, possess the G2-property. This generalizes results of Hartshorne and B\u{a}descu-Schneider.

Algebraic Geometry · Mathematics 2018-05-17 Mihai Halic

We characterize embeddability of algebraic varieties into smooth toric varieties and prevarieties. Our embedding results hold also in an equivariant context and thus generalize a well known embedding theorem of Sumihiro on quasiprojective…

Algebraic Geometry · Mathematics 2007-05-23 Juergen Hausen

We show that if $X$ is a smooth uniruled projective variety and $L$ a big and semiample $\mathbb{Q}$-divisor on $X$, then there exists a proper closed subset $W\subset X$ such that every subvariety $Y$ satisfying $a(Y,L)> a(X,L)$ is…

Algebraic Geometry · Mathematics 2017-11-27 Christopher D. Hacon , Chen Jiang

We show that ample line bundles L on a g-dimensional simple abelian variety, with h^0(L)> 2^g.g!, give projectively normal embeddings, for all g>0.

Algebraic Geometry · Mathematics 2007-05-23 Jaya N. Iyer

In this paper, we prove the holomorphic convexity of the covering of a complex projective {normal} variety $X$, which corresponds to the intersection of kernels of reductive representations $\rho:\pi_1(X)\to {\rm GL}_{N}(\mathbb{C})$,…

Algebraic Geometry · Mathematics 2024-05-30 Ya Deng , Katsutoshi Yamanoi , Ludmil Katzarkov

It is shown that a complex normal projective variety has non-positive Kodaira dimension if it admits a non-isomorphic quasi-polarized endomorphism. The geometric structure of the variety is described by methods of equivariant lifting and…

Algebraic Geometry · Mathematics 2018-09-24 Noboru Nakayama , De-Qi Zhang

We propose a framework to give a precise meaning to the intuitive notion of "family of real forms of a variety parametrised by a variety" and study some fundamental properties of this notion. As an illustration, for any $n \geq 1$, we…

Algebraic Geometry · Mathematics 2023-05-22 Anna Bot , Adrien Dubouloz