Monopoly”. While many colleagues have provided valuable and in some cases detailed comments, special debts are due to Kevin Murphy (who originally inspired the work), Tony Atkinson and Faruk Gul (for suggesting the subtitle and title of the article, respectively), Luciano de Castro and Michael Salinger (for excellent formal conference discussions), Mark Armstrong, David Atkin and Dave Donaldson (for suggesting new results), Jesse Shapiro (for suggesting ways of reframing the paper) and above all Jeremy Bulow (for more things than can be listed here). Weyl is grateful