Some recent literature on "vertical product differentiation" has d eveloped the idea that if the nature of technology and tastes in some industry take a certain form, then the industry must necessarily be "concentrated" and must remain so, no matter how large the economy becomes. The present...

A model of a population with a Local Interaction structure is presented. Individuals interact with others in a given Interaction neighborhood to obtain their payoff. Individuals either imitate or else they die and are replaced by one of their neighbors in another neighborhood- the Propagation...