The authors propose a specific characteristics framework in order to construct linkages between alternative approaches to modeling product differentiation. It is shown that a demand system that satisfies the gross substitutes property imposes specific requirements on the locations of products....

Producers' anticipations of paying monopoly fees for infrastructure services dampen their incentive to invest and may prevent the economy from reaching a minimal level of activity that would justify investment in a large indivisible infrastructure; and potential investors in infrastructure may be...