We investigate whether the L¹-algebra of polynomial hypergroups has non-zero bounded point derivations. We show that the existence of such point derivations heavily depends on growth properties of the Haar weights. Many examples are studied in detail. We can thus demonstrate that the L¹-algebras of hypergroups have properties (connected with amenability) that are very different from those of groups.
Institute of Biomathematics and Biometry, Helmholtz National Research Center for Environment and Health, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
Centre of Mathematics, Munich University of Technology, 85748 Garching, Germany