Protocols for automated negotiations with buyer anonymity and seller reputations

In many Internet commerce applications buyers can easily achieve anonymity, limiting what a seller can learn about any buyer individually. However, because sellers need to keep a fixed web address, buyers can probe them repeatedly or pool their information about sellers with the information obtained by other buyers; hence, sellers' strategies become public knowledge. Under assumptions of buyer anonymity, publicly‐known seller strategies, and no negotiation transaction costs for buyers, we find that take‐it‐or‐leave‐it offers will yield at least as much seller profit as any attempt at price discrimination could yield. As we relax those assumptions, however, we find that sellers, and in some cases buyers as well, may benefit from a more general bargaining protocol. This revised version was published online in June 2006 with corrections to the Cover Date.