Tannaka duality and formal glueings
By Jack Hall
Also appears in collection : Jean Morlet Chair: Artin approximation and Infinite Dimensional Geometry / Chaire Jean Morlet : approximation de Artin et géométrie en dimension infinie
After recalling classical Tannaka duality for finite groups, I will discuss an extension to equivariant algebraic geometry, and more generally to algebraic stacks. Surprisingly, this is related to formal glueings and Neron-Popescu desingularization.