## Tannaka duality for comodules over a Hopf algebra

### Steve Bennoun – 7 March 2007

In this talk, I shall define the category of comodules over a bialgebra A and prove that it is autonomous when A is a Hopf algebra. Then, starting with this category, I shall use Tannaka duality to reconstruct the bialgebra A. This will naturally lead to a construction for freely adjoining an invertible antipode to a bialgebra.
A video of the talk is available.

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