Gullibility is the principal cause of bubbles. Investors and the general public get snared by a "beautiful illusion" and throw caution to the wind. Attempts to identify and control bubbles are complicated by the fact that the authorities who might naturally be expected to take action have often...

We investigate the existence and implications of competitive equilibria when two firms offer the same electronic goods under different pricing policies. One charges a fixed subscription fee per period; the other charges on a per-use basis. Two models are examined when firms' marginal costs are...

The routes of early railways around the world were generally inefficient because the prevailing doctrine of the time called for concentrating on provision of fast service between major cities and neglect of local traffic. Modern planners rely on methods such as the "gravity models of spatial...