6 papers
Cohomological invariants of root stacks and admissible double coverings
Andrea Di Lorenzo, Roberto Pirisi
We give a formula for the cohomological invariants of a root stack, which we apply to compute the cohomological invariants and the Brauer group of the stack of admissible double co…
Brauer groups of moduli of hyperelliptic curves via cohomological invariants
Andrea Di Lorenzo, Roberto Pirisi
We compute the Brauer group of the moduli stack of hyperelliptic curves over any field of characteristic zero. In positive characteristic, we compute the part of th…
A complete description of the cohomological invariants of even genus hyperelliptic curves
Andrea Di Lorenzo, Roberto Pirisi
When the genus is even, we extend the computation of mod 2 cohomological invariants of to non algebraically closed fields, we give an explicit functorial descri…
The Brauer group of the universal moduli space of vector bundles over smooth curves
Roberto Fringuelli, Roberto Pirisi
We compute the Brauer group of the universal moduli stack of vector bundles on (possibly marked) smooth curves of genus at least three over the complex numbers. As consequence, we…
Gabriel's theorem and birational geometry
John Calabrese, Roberto Pirisi
Extending work of Meinhardt and Partsch, we prove that two varieties are isomorphic in codimension c if and only if certain quotients of their categories of coherent sheaves are eq…
The Picard group of the universal abelian variety and the Franchetta conjecture for abelian varieties
Roberto Fringuelli, Roberto Pirisi
We compute the Picard group of the universal abelian variety over the moduli stack of principally polarized abelian varieties over with a symplectic…