The Green ring of a family of copointed Hopf algebras

The copointed liftings of the Fomin-Kirillov algebra F K 3 over the algebra of functions on the symmetric group S 3 were classied by Andruskiewitsch and the author.We demonstrate here that those associated to a generic parameter are Morita equivalent to the regular blocks of well-known Hopf algebras: the Drinfeld doubles of the Taft algebras and the small quantum groups uq(sl 2 ).The indecomposable modules over these were classied independently by Chen, ChariPremet and Suter.Consequently, we obtain the indocomposable modules over the generic liftings of F K 3 .We decompose the tensor products between them into the direct sum of indecomposable modules.We then deduce a presentation by generators and relations of the Green ring.