Subscription mechanisms for network formation.

We analyze a model of network formation where the costs of forming links are publicly known but an individual's benefits are not known to the social planner. The objective is to design a mechanism which not only ensures that an efficient network always forms in equilibrium but also ensures that the resulting net payoffs to the agents are equitable. We propose two mechanisms towards this end; in the first, agents announce sequentially the set of players with whom they wish to form links and a cost contribution. We show that all subgame perfect equilibria of this game result in the formation of an efficient network but the resulting net payoffs are asymmetric. The second mechanism corrects this asymmetry through a two-stage variant of the first mechanism. We also discuss an extension of the basic model to cover the case of directed graphs and give conditions under which the proposed mechanisms are immune to deviations by coalitions.