Multiproduct Cournot oligopoly

We study a Cournot industry in which each firm sells multiple quality-differentiated products. We use an upgrades approach, working not with the actual products but instead with upgrades from one quality to the next. The properties of single-product models carry over to the supply of upgrades, but not necessarily to the supply of complete products. Product line determinants and welfare results are presented. Strategic commitment to product lines is considered; firms may well choose to compete head-to-head.