5 papers · 1 filter
Refined index obstructions for Brauer classes on an abelian variety
Eoin Mackall
We produce refined index obstructions, generalizing recently constructed index obstructions due to de Jong and Perry, for topologically trivial Brauer classes on smooth and project…
An algorithmic reduction to canonical forms for vector bundles on anisotropic conics
Eoin Mackall, Diego Yépez
We describe a polynomial complexity algorithm for reducing transition matrices, for vector bundles glued along a clutching-type cover of a real anisotropic conic, to canonical bloc…
A Looming of phantoms
Kimoi Kemboi, Daniel Krashen, Tianle Liu +6
Following Krah's method, we construct new examples of phantom categories as semiorthogonal components of the derived categories of two types of rational surfaces: the blowup of the…
The Period and Index of a Generic Geometrically Elliptic Normal Curve
Eoin Mackall
We construct genus one curves on base extensions of generic Severi--Brauer varieties of a given index and period which are versal objects for families of geometrically elliptic nor…
On deformations of Azumaya algebras with quadratic pair
Eoin Mackall, Cameron Ruether
We construct a tangent-obstruction theory for Azumaya algebras equipped with a quadratic pair. Under the assumption that either 2 is a global unit or the algebra is of degree 2, we…