Torsion bounds for Drinfeld modules with complex multiplication.

In this talk we introduce the notion of an elementary abelian closure, we show that it exists and is unique for any non-cyclic biquadratic field extension. We make use of it to obtain a classification for this class of extensions up to isomorphism via descent. This permits us to describe the geometry of this moduli space in group theoretic terms. Some part of the content to be presented can be found on The geometry of the moduli Space of non-cyclic biquadratic field extensions.