11 citations · 15 across the 10 of their papers we have counts for
13 papers
Ramified periods and field of definition
Giuseppe Ancona, Dragoş Frăţilă, Alberto Vezzani
Let be an extension of number fields that is ramified above . We give a new obstruction to the descent to of smooth projective varieties defined over . The obstruct…
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…
Ngô support theorem and polarizability of quasi-projective commutative group schemes
Giuseppe Ancona, Dragos Fratila
We prove that any commutative group scheme over an arbitrary base scheme of finite type over a field with connected fibers and admitting a relatively ample line bundle is polarizab…
Relative and absolute Lefschetz standard conjectures for some Lagrangian fibrations
Giuseppe Ancona, Mattia Cavicchi, Robert Laterveer +1
We show that the hyper-Kähler varieties of OG10-type constructed by Laza-Saccà-Voisin (LSV) verify the Lefschetz standard conjecture. This is an application of a more general resul…
Some arithmetic and geometric aspects of algebraic cycles and motives
Giuseppe Ancona
This is my habilitation thesis. As the tradition wants, I tried to give an introduction of my field of research. I post it on the ArXiv with the hope it can be useful to young rese…
The Hilbert symbol in the Hodge standard conjecture
Giuseppe Ancona, Adriano Marmora
We study the Hodge standard conjecture for varieties over finite fields admitting a CM lifting, such as abelian varieties or products of K3 surfaces. For those varieties we show th…
Algebraic classes in mixed characteristic and André's p-adic periods
Giuseppe Ancona, Dragos Fratila
Motivated by the study of algebraic classes in mixed characteristic we define a countable subalgebra of which we call the algebra of André's -adic periods.…
Standard conjectures for abelian fourfolds
Giuseppe Ancona
Let A be an abelian fourfold. We prove the Standard Conjecture of Hodge type for A. By combining this result with a theorem of Clozel we deduce that numerical equivalence on A coin…
Conservativity of realizations on motives of abelian type over finite fields
Giuseppe Ancona
We show that the l-adic realization functor is conservative when restricted to the Chow motives of abelian type over a finite field. A weak version of this conservativity result ex…
Numerical functors on Voevodsky's motives
Giuseppe Ancona
We study mixed versions of the classical quotient functor from Chow motives to numerical motives. We compare two natural definitions, which turn out to be very different. We invest…
On the relative motive of a commutative group scheme
Giuseppe Ancona, Annette Huber, Simon Pepin Lehalleur
We prove a canonical Kuenneth decomposition of the relative motive with rational coefficients of a smooth commutative group scheme over a noetherian finite dimensional base. This…
Degeneration of Hodge structures over Picard modular surfaces
Giuseppe Ancona
We study variations of Hodge structures over a Picard modular surface, and compute the weights and types of their degenerations through the cusps of the Baily-Borel compactificatio…
On the motive of a commutative algebraic group
Giuseppe Ancona, Stephen Enright-Ward, Annette Huber
We prove a canonical Kunneth decomposition for the motive of a commutative group scheme over a field. Moreover, we show that this decomposition behaves under the group law just as…