Une approche générale de l'externalité dans un réseau de communication

The existence of a communication network induces an externality among the agents of an economy. In this paper, we study the network externality whithin a new framework which extends models used in the literature. It allows to take into account many features of the interest of the consumers in the network and not only the network size as it was done in previous works. We define the global access demand to the network by using the household disposal to be connected to the network and the maximal surplus provided by the network to the agents. A network state of equilibrium is defined as a fixed-point of the mapping which associates to a network the global access demand. After having shown that the empty state is an equilibrium, we give a necessary and sufficient condition for the existence of a non-empty equilibrium state. We then study the dynamic around an equilibrium state and we give a sufficient condition for local stability.