A feasible social state is irreducible if and only if, for any non-trivial partition of individuals into two groups, there exists another feasible social state at which every individual in the first group is equally well-off and someone strictly better-off. Competitive equilibria decentralize...

We show that in almost every economy with separable externalities, every competitive equilibrium can be Pareto improved by a package of anonymous commodity taxes that cause prices to adjust and markets to reclear at different levels of individual consumption. The argument can be extended to...

Equilibrium paths in economies of overlapping generations depend on the frequency of trade. In a standard example, determinacy obtains as the frequency of trades tends to infinity or trade occurs in continuous time. If time extends infinitely into the infinite past as well as into the infinite...

Money provides liquidity services through a cash-in-advance constraint. The exchange of commodities and assets extends over an infinite horizon under uncertainty and a complete asset market. Monetary policy sets the path of rates of interest and accommodates the demand for balances. Competitive...

We characterize the equilibrium manifold of an economy when initial endowments can be individually observed. We adopt a local, "differentiable" perspective. We derive necessary and sufficient conditions that characterize the equilibrium manifold, and we show that, if these conditions are...