For simple economic models of transfrontier pollution, Chander and Tulkens (1995) and (1997) have offered a formula for transfers to sustain international cooperation on a voluntary basis and which deter coalitionnal free-riding under some reasonable behaviours of countries not in the coalition....

We analyze a game in which a group of agents exert costly effort over time to make progress on a project. The project is completed once the cumulative efforts reach a pre-specified threshold, at which point it generates a lump sum payoff. We characterize a budget balanced mechanism that induces...