This paper explores the fault line that separates communication failure from success when message meaning is compromised because there is mutual but not common knowledge of which messages are available. If the size of the message space is just sufficient to convey all payoff-relevant private...

We study tacit collusion in repeated auctions in which bidders can only observe pastwinners and not their bids. We adopt a stringent interpretation of tacit collusion ascollusion without communication about strategies that we model as a symmetryrestriction on repeated game strategies: Strategies...