Computing the equivariant Brauer group

Abstract

Let X be a smooth projective rational variety carrying a regular action of a finite abelian group G. We give examples of effective computation of the Brauer group of the quotient stack [X/G] in dimensions 2 and 3 using residues in Galois cohomology and the geometry of fixed loci. In particular, we compute Br([X/G]) for all G-minimal del Pezzo surfaces.

40 pages