노트 : This paper derives from extensive notes used for a lecture and related seminar given April 18, 2000 at Macalester
College, St. Paul, Minnesota under the auspices of its Economics Department's Cargill Distinguished Visitor Program; thanks are due to Macalester's economics faculty for their invitation leading to the paper. Some of the work discussed herein was supported by the United Nations University, Institute for New Technologies, Maastricht, the Netherlands, and by the Joel Dean Foundation's funding of summer research by Swarthmore students in the social sciences; Esther Parker ’97 provided exceptionally able research assistance in the doing of the work
