The cloud computing paradigm gives rise to Web service marketplaces where complex services areprovided by several modular vendors. Recently more and more intermediaries are pushing onto themarket, thereby driving competition. Offering innovative business models which are capable ofattracting...

In this paper we axiomatically characterize two recursive procedures for defining a social group. The first procedure starts with the set of all individuals who are defined by everyone in the society as group members, while the starting point of the second procedure is the set of all individuals...