We analyze economies in which individuals specialize in consumption and production and meet randomly over time in a way that implies that trade must be bilateral and quid pro quo. Nash equilibria in trading strategies are characterized. Certain goods emerge endogenously as media of exchange, or commodity money, depending both on their intrinsic properties and on extrinsic beliefs. There are also equilibria with genuine fiat currency circulating as the general medium of exchange. We find that equilibria are not generally Pareto optimal and that introducing fiat currency into a commodity money economy may unambiguously improve welfare. Velocity, acceptability, and liquidity are discussed.

We analyze two unemployment insurance systems. In one, unemployed workers receive benefits while those on reduced hours do not, as in North America (at least until recently). In the other, short-time compensation is paid to workers on reduced hours, as in Europe. The first system causes inefficient temporary layoffs for some parameters; the latter does not, but implies inefficient hours per worker. Some evidence is presented regarding these effects. Despite policymakers' recent enthusiasm for short-time compensation, the clear implication of this project is that changes should come on the tax, not benefit, side of the system.

We analyze two unemployment insurance systems. In one, unemployed workers receive benefits while those on reduced hours do not, as in North America (at least until recently). In the other, short-time compensation is paid to workers on reduced hours, as in Europe. The first system causes inefficient temporary layoffs for some parameters; the latter does not, but implies inefficient hours per worker. Some evidence is presented regarding these effects. Despite policymakers' recent enthusiasm for short-time compensation, the clear implication of this project is that changes should come on the tax, not benefit, side of the system.

The authors analyze economies in which individuals specialize in consumption and production and meet randomly over time in a way that implies that trade must be bilateral and quid pro quo. Nash equilibria in trading strategies are characterized. Certain goods emerge endogenously as media of exchange, or commodity money, depending both on their intrinsic properties and on extrinsic beliefs. There are also equilibria with genuine fiat currency circulating as the general medium of exchange. The authors find that equilibria are not generally Pareto optimal and that introducing fiat currency into a commodity money economy may unambiguously improve welfare. Velocity, acceptability, and liquidity are discussed.