Emiliano Ambrosi

activity

20172025

most citedMaximal tori of monodromy groups of

F

-isocrystals and an application to abelian varieties

7 citations · 15 across the 13 of their papers we have counts for

collaborators

13 papers

math.AG2025

Wild Brauer classes via prismatic cohomology

Emiliano Ambrosi, Rachel Newton, Margherita Pagano

Let $K$ be a finite extension of $Q_{p}$ and $X$ a smooth proper $K$ -variety with good reduction. Under a mild assumption on the behaviour of Hodge numbers under reduction m…

math.AG2025

Topological groupoids with involution and real algebraic stacks

Emiliano Ambrosi, Olivier de Gaay Fortman

To a topological groupoid endowed with an involution, we associate a topological groupoid of fixed points, generalizing the fixed-point subspace of a topological space with involut…

math.AG2025

On the topology of real algebraic stacks

Emiliano Ambrosi, Olivier de Gaay Fortman

Motivated by questions arising in the theory of moduli spaces in real algebraic geometry, we develop a range of methods to study the topology of the real locus of a Deligne-Mumford…

math.AG2025

An Artin--Mumford criterion for conic bundles in characteristic two

Emiliano Ambrosi, Giuseppe Ancona

We prove a characteristic two version of the famous criterion of Artin and Mumford for irrationality of conic bundles. On the one hand, combined with the pathological behaviour of…

math.NT2025

Geometrically simple counterexamples to a local-global principle for quadratic twists

Emiliano Ambrosi, Nirvana Coppola, Francesc Fité

Two abelian varieties $A$ and $B$ over a number field $K$ are said to be strongly locally quadratic twists if they are quadratic twists at every completion of $K$ . While it was kno…

math.AG2023

Reduction modulo $p$ of the Noether problem

Emiliano Ambrosi, Domenico Valloni

Let $R$ be a complete valuation ring of mixed characteristic $(0, p)$ with algebraically closed fraction field $K$ and residue field $k$ . Let $X / R$ be a smooth projective morphism.…

math.AG2022★ 1 cited

Betti numbers of real semistable degenerations via real logarithmic geometry

Emiliano Ambrosi, Matilde Manzaroli

Let $X \to C$ be a totally real semistable degeneration over a smooth real curve $C$ with degenerate fiber $X_{0}$ . Assuming that the irreducible components of $X_{0}$ are simpl…

math.NT2021★ 2 cited

Perfect points of abelian varieties

Emiliano Ambrosi

Let $k$ be an algebraic extension of $F_{p}$ and $K / k$ a regular extension of fields (e.g. $F_{p} (T) / F_{p}$ ). Let $A$ be a $K$ -abelian variety such that all the i…

math.NT2019

Uniform boundedness for Brauer groups of forms in positive characteristic

Emiliano Ambrosi

Let $k$ be a finitely generated field of characteristic $p > 0$ and $X$ a smooth and proper scheme over $k$ . Recent works of Cadoret, Hui and Tamagawa show that, if $X$ satisfies the…

math.NT2018★ 7 cited

Maximal tori of monodromy groups of $F$ -isocrystals and an application to abelian varieties

Emiliano Ambrosi, Marco D'Addezio

Let $X_{0}$ be a smooth geometrically connected variety defined over a finite field $F_{q}$ and let $E_{0}^{†}$ be an irreducible overconvergent $F$ -isocrystal on…

math.AG2018★ 1 cited

Specialization of Néron-Severi groups in positive characteristic

Emiliano Ambrosi

Let $k$ be an infinite finitely generated field of characteristic $p > 0$ . Fix a separated scheme $X$ smooth, geometrically connected, and of finite type over $k$ and a smooth proper…

math.AG2018★ 4 cited

A note on the behaviour of the Tate conjecture under finitely generated field extensions

Emiliano Ambrosi

We show that the $ℓ$ -adic Tate conjecture for divisors on smooth proper varieties over finitely generated fields of positive characteristic follows from the $ℓ$ -adic Tate con…

math.NT2017

A uniform open image theorem for l-adic representations in positive characteristic

Emiliano Ambrosi

Let $k$ be a finitely generated field of characteristic $p > 0$ and $ℓ$ a prime. Let $X$ be a smooth, separated, geometrically connected curve of finite type over $k$ and $ρ: π_…

Wild Brauer classes via prismatic cohomology

Topological groupoids with involution and real algebraic stacks

On the topology of real algebraic stacks

An Artin--Mumford criterion for conic bundles in characteristic two

Geometrically simple counterexamples to a local-global principle for quadratic twists

Reduction modulo p of the Noether problem

Betti numbers of real semistable degenerations via real logarithmic geometry

Perfect points of abelian varieties

Uniform boundedness for Brauer groups of forms in positive characteristic

Maximal tori of monodromy groups of F-isocrystals and an application to abelian varieties

Specialization of Néron-Severi groups in positive characteristic

A note on the behaviour of the Tate conjecture under finitely generated field extensions

A uniform open image theorem for l-adic representations in positive characteristic

Reduction modulo $p$ of the Noether problem

Maximal tori of monodromy groups of $F$ -isocrystals and an application to abelian varieties