Bonneau P., Flato M., Gerstenhaber M., Pinczon G.
The hidden group structure of quantum groups: strong duality,
rigidity and preferred deformations.
(130K, plain TeX)

ABSTRACT.  A notion of well-behaved Hopf algebra is introduced;
reflexivity (for strong duality) between Hopf algebras
of Drinfeld-type and their duals, algebras of coefficients
of compact semi-simple groups, is proved.
A hidden classical group structure is clearly indicated for
all generic models of quantum groups.
Moyal-product-like deformations are naturally found for all
FRT-models on coefficients and $C^\infty$-functions.
Strong rigidity ($H^2_{bi} = \{ 0 \}$) under deformations
in the category of bialgebras is proved and consequences
are deduced.