On strongly negative definite functions for the product of commutative hypergroups (Q2896996)

The authors consider negative definite functions and a Lévy-Khintchine representation for products of certain commutative hypergroups.NEWLINENEWLINEThe paper should not have been published in this form: It contains several incorrect definitions, statements, and citations. E.g., it is not clear why the authors consider some technical property of direct products in Lemma 11, where this property does not appear before, and why they consider direct products and not just simply commutative hypergroups satisfying certain restrictions which are preserved under direct products.NEWLINENEWLINEBy the way, the best known results on the Lévy-Khintchine representation on hypergroups were obtained in papers of Christian Rentzsch.