Duality theorems for graded algebras and coalgebras (Q1359027)

The paper deals with the study of duality for the smash product (or coproduct) associated to a \(G\)-set and a \(G\)-graded algebra (or coalgebra), where \(G\) is a group. Endomorphism rings are also studied. The approach and methods of this paper (e.g. the example showing that the Cohen-Montgomery duality does not necessarily hold for \(G\)-sets, or the use of Hopf modules over the group algebra) bring new information on both the particular case of \(G\)-gradings and the general case of Hopf algebra actions.