MULTIPRODUCT CLUBS - MEMBERSHIP AND SUSTAINABILITY

Club theory is extended to the case of multiproduct clubs. Multiproduc t club structure varies depending on whether members are restricted to consume all of the club's products, and whether the club is sustainab le against other clubs providing the entire package of products or a s ubset. Membership of the multiproduct club is contrasted to that of al ternative clubs serving a subset of products. Necessary conditions for sustainability are related to cost subadditivity and membership restr ictions. The integer problem and the instability that it entails for c lub memberships are more troublesome for multiproduct clubs, because t he population must be partitioned by both products and clubs.