A model of English auctions is proposed to incorporate the possibility of jump bidding. When two objects are sold separately via such auctions, bidders signal their willingness to pay via jump bids, thereby forming rational expectations of the prices without relying on any central mediator....

We consider collective choice from two alternatives. Ex-ante, each agent is uncertain about which alternative she prefers, and may be uncertain about the intensity of her preferences. An environment is given by a probability distribution over utility vectors that is symmetric across agents and...