We consider an "arms race" game, where two players simultaneously decide whether or not to aquire new weapons. Each player has a type, which is his private information. Types are independent. With probability close to one, the best outcome for each player is for neither to acquire new weapons...

We study the implementation problem for exchange economies when agents can renegotiate the outcome assigned by the planner and can collude. We focus on the use of sequential mechanisms and present a simple sufficient condition for implementation with renegotiation in strong perfect equilibrium....