We develop a simple model of the exchange rate in which agents optimize their portfolio and use different forecasting rules. They check the profitability of these rules ex post and select the more profitable one. This model produces two kinds of equilibria, a fundamental and a bubble one. In a...

We develop a simple model of the exchange rate in which agents optimize their portfolio and use different forecasting rules. They check the profitability of these rules ex post and select the more profitable one. This model produces two kinds of equilibria, a fundamental and a bubble one. In a...

This paper traces the 11,000 year evolution of infrastructure systems during major periods of innovation, expansion and diffusion. Throughout history, the key role of the State is self-evident. Private sector involvement has waxed and waned over millennia, although at times it has been pivotal...