Consider an exchange economy with a finite number of agents, who are arbitragers, in that they try to upset allocations imagining plausible beneficial trades. Their thought process is interactive, in that agents are conscious that the others are also going through the same steps. With this...

In contexts in which players have no priors, we analyze a learning process based on ex-post regret as a guide to understand how to play games of incomplete information under private values. The conclusions depend on whether players interact within a fixed set (fixed matching) or they are...