Aside from the equilibrium that Hotelling (1931) displayed, his model of non-renewable resources also contains a continuum of bubble equilibria. In all the equilibria the price of the resource rises at the rate of interest. In a bubble equilibrium, however, the consumption of the resource peters...

This paper models the product cycle and explains how it relates to world inequality. In the model, both phenomena arise because skilled people have a comparative advantage in making high-tech products. The model can explain up to a 10:1 income differential between people and up to a 7:1...

If machines are indivisible, a vintage capital model must give rise to income inequality. If new machines are always better than old ones and if society cannot provide everyone with a new machine all of the time, inequality will result. I explore this mechanism in detail. If technology resides...

In this survey, I discuss four sources of growth of knowledge: research, schooling, learning by doing, and training. In trying to disentangle what is important, I emphasize the following facts: (1) even the most advanced countries spend far more on adoption of existing technologies than on...

This paper derives an indirect production function that is, in a special case, of a constant elasticity of substitution form. This is not a contribution to the theory of aggregation generally. Instead it is a microfoundation for a specific but popular production function -- the CES -- that helps...

The prospect of capital obsolescence inhibits investment. Investors thus become more optimistic when the obsolescence of their capital slows down. We propose a model with no fixed costs of investment, and random technological progress that induces obsolescence of capital in place. Spikes occur...

We study the effects of parameter uncertainty prompted by structural breaks. In our model, agents respond differently to uncertainty prompted by regime shifts in shock processes than they react to comparable perceived increases in shock volatility. The magnitude of the response to an increase in...

We study private equity in a dynamic general equilibrium model and ask two questions: (i) Why does the investment of venture funds respond more strongly to the business cycle than that of buyout funds? (ii) Why are venture funds returns higher than those of buyout? On (i), venture brings in new...

We provide a model that links the high return to venture equity to the impatience of the VCs. VCs are scarce, and hence, they have market power and a high return on their investments. As a result, VCs are eager to terminate non-performing ventures so they can move on to new ones. The scarcity of...