Marco Antei

activity

20082018

most citedNori fundamental gerbe of essentially finite covers and Galois closure of towers of torsors

2 citations · 8 across the 12 of their papers we have counts for

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16 papers · 1 filter

math.AG2018

Models of torsors over affine spaces

Marco Antei, Jorge A. Esquivel A

Let $X := A_{R}^{n}$ be the $n$ -dimensional affine space over a discrete valuation ring $R$ with fraction field $K$ . We prove that any pointed torsor $Y$ over $\mathbb{A}^{n…

math.AG2017★ 2 cited

Nori fundamental gerbe of essentially finite covers and Galois closure of towers of torsors

M. Antei, I. Biswas, M. Emsalem +2

We prove the existence of a Galois closure for towers of torsors under finite group schemes over a proper, geometrically connected and geometrically reduced algebraic stack $X$ ove…

math.AG2016★ 2 cited

Towers of torsors over a field

Marco Antei, Indranil Biswas, Michel Emsalem

Let $X$ be a projective, connected and smooth scheme defined over an algebraically closed field $k$ . In this paper we prove that a tower of finite torsors (i.e., under the action o…

math.AG2016

Models of torsors and the fundamental group scheme

Marco Antei, Michel Emsalem

Given a relative faithfully flat pointed scheme over the spectrum of a discrete valuation ring $X \to S$ this paper is motivated by the study of the natural morphism from the funda…

math.AG2016

The pseudo-fundamental group-scheme

Marco Antei, Arijit Dey

Let $X$ be any scheme defined over a Dedekind scheme $S$ with a given section $x \in X (S)$ . We prove the existence of a pro-finite $S$ -group scheme $ℵ (X, x)$ and a universal $\a…

math.AG2015

On the bumpy fundamental group scheme

Marco Antei

In this short paper we first recall the definition and the construction of the fundamental group scheme of a scheme $X$ in the known cases: when it is defined over a field and when…

math.AG2014★ 1 cited

On the fundamental group scheme of rationally chain connected varieties

Marco Antei, Indranil Biswas

Let $k$ be an algebraically closed field. Chambert-Loir proved that the étale fundamental group of a normal rationally chain connected variety over $k$ is finite. We prove that the…

math.AG2012

Models of torsors over curves

Marco Antei

Let $R$ be a complete discrete valuation ring with fraction field $K$ and with algebraically closed residue field. Let $X$ be a faithfully flat $R$ -scheme of finite type of relativ…

math.AG2012

Pushout of quasi-finite and flat group schemes over a Dedekind ring

Marco Antei

Let $G$ , $G_{1}$ and $G_{2}$ be quasi-finite and flat group schemes over a complete discrete valuation ring $R$ , $φ_{1} : G \to G_{1}$ any morphism of $R$ -group schemes and $φ_{2} : G \to G_{2}$ a m…

math.AG2011

On the Grothendieck-Lefschetz Theorem for a Family of Varieties

Marco Antei, Vikram Mehta

Let $k$ be an algebraically closed field of characteristic $p > 0$ , $W$ the ring of Witt vectors over $k$ and $R$ the integral closure of $W$ in the algebraic closure $K ˉ$ o…

math.AG2010★ 2 cited

Extention of Finite Solvable Torsors over a Curve

Marco Antei

Let $R$ be a discrete valuation ring with fraction field $K$ and with algebraically closed residue field of positive characteristic $p$ . Let $X$ be a smooth fibered surface over $R…

math.AG2010

The Fundamental Group Scheme of a non Reduced Scheme

Marco Antei

We extend the definition of fundamental group scheme to non reduced schemes over any connected Dedekind scheme. Then we compare the fundamental group scheme of an affine scheme wit…

math.AG2010★ 1 cited

Vector Bundles over Normal Varieties Trivialized by Finite Morphisms

Marco Antei, Vikram Mehta

Let $Y$ be a normal and projective variety over an algebraically closed field $k$ and $V$ a vector bundle over $Y$ . We prove that if there exist a $k$ -scheme $X$ and a finite surje…

math.AG2009

On the Abelian Fundamental Group Scheme of a Family of Varities

Marco Antei

Let $S$ be a connected Dedekind scheme and $X$ an $S$ -scheme provided with a section $x$ . We prove that the morphism of fundamental group schemes $π_1(X,x)^{ab}\to π_1(\mathbf{Alb}…

math.AG2009

Galois Closure of Essentially Finite Morphisms

Marco Antei, Michel Emsalem

Let $X$ be a reduced connected $k$ -scheme pointed at a rational point $x \in X (k)$ . By using tannakian techniques we construct the Galois closure of an essentially finite $k$ -morph…

math.AG2008

Comparison between the fundamental group scheme of a relative scheme and that of its generic fiber

Marco Antei

We show that the natural morphism $ϕ : π_{1} (X_{η}, x_{η}) \to π_{1} (X, x)_{η}$ between the fundamental group scheme of the generic fiber $X_{η}$ of a scheme $X$ over a connected Dedekind scheme an…