We study mechanism design with flexible but costly information acquisition. There is a principal and four or more agents, sharing a common prior over the set of payoff-relevant states. The principal proposes a mechanism to the agents who can then acquire information about the state of the world...

I consider a repeated auction setting with colluding buyers and a seller who adjusts reserve prices over time without long-term commitment. To model the seller's concern for collusion, I introduce a new equilibrium concept: collusive public perfect equilibrium. For every strategy of the seller I...