Essays in industrial organization

This thesis is composed by three different studies on oligopolies. The first chapter is on oligopolies with perfect complements; the second chapter studies oligopolies with positive network effects and incompatible networks, and the last one deals with a polluting duopoly subject to environmental regulation. Specifically, the first chapter provides a thorough characterization of the properties of Cournot’s complementary monopoly model (or oligopoly with perfect complements) in a general setting, including existence, uniqueness and the comparative statics effects of entry. As such, this serves to unify various results from the extant literature that have typically been derived with limited generality. Several studies have suggested that Cournot’s complementary monopoly model is the dual problem to the standard Cournot oligopoly model. This result crucially relies on the assumption that the firms have no production costs. The first chapter shows that if the production costs of the firms are different from zero, the nice duality between these two oligopoly settings breaks down. One implication of this breakdown is that, in contrast to the Cournot model, oligopoly with perfect complements can be a game of strategic complements in a global sense even in the presence of production costs. The second chapter models symmetric oligopolies with positive network effects where each firm has its own proprietary network. That is, each firm’s network is incompatible with that of its rivals. This chapter provides minimal conditions for