Bijective combinatorial proof of the commutation of transfer matrices in the dense O(1) loop model

The dense O(1) loop model is a statistical physics model with connections to the quantum XXZ spin chain, alternating sign matrices, the six-vertex model and critical bond percolation on the square lattice. When cylindrical boundary conditions are imposed, the model possesses a commuting family of transfer matrices. The original proof of the commutation property is algebraic and is based on the Yang-Baxter equation. In this paper we give a new proof of this fact using a direct combinatorial bijection.Comment: 18 pages, many figure

Insulation Impossible: Monetary Policy and Regional Fiscal Spillovers in a Federation

This paper studies the interactions of fiscal and monetary policies in the presence of fiscal spillovers within a monetary union. When capital markets are integrated, the fiscal policy of any member country will influence equilibrium wages and interest rates across the whole union. Thus there are fiscal spillovers within a federation. Within a general class of monetary policy rules, there does not exist one that completely insulates agents in one region from fiscal policy in another. We contrast particular rules, such as inflation and interest rate targeting, to illustrate how monetary policy becomes a channel for fiscal policy spillovers.Fiscal spillovers; Monetary union

Trade Agreements, Bargaining and Economic Growth

Rebelo's two-sector endogenous growth model is embedded within a two-country international trade framework. The two countries bargain over a trade agreement that specifies: (i) the size of the foreign aid that the richer country gives to the poorer one; (ii) the terms of the international trade that takes place after the aid is given. The aid is given not because of generosity, but because it improves the capital allocation across the world and thus raises total world production. This world production surplus enables the rich country to raise its equilibrium consumption and welfare beyond their no-aid levels. To ensure it, the rich country uses a trade agreement to condition the aid on favorable terms of trade.International trade, Aid, Balanced Growth, Trade Agreement

Insulation Impossible: Fiscal Spillovers in a Monetary Union

This paper studies fiscal spillovers in a monetary union. The focus of the analysis is on the interaction between the fiscal policy of member countries (regions) and the central monetary authority. When capital markets are integrated, the fiscal policy of one country will inuence equilibrium wages and interest rates. Thus there are fiscal spillovers within a federation. The magnitude and direction of these spillovers, in particular the presence of a crowding out effect, can be inuenced by the choice of monetary policy rules. We find that there does not exist a monetary policy rule which completely insulates agents in one region from fiscal policy in another. Some familiar policy rules, such as pegging an interest rate, can provide partial insulation.

Is It Is or Is It Ain't My Obligation? Regional Debt in a Fiscal Federation

This paper studies the repayment of regional debt in a multi-region economy with a central authority: who pays the obligation issued by a region? With commitment, a central government will use its taxation power to smooth distortionary taxes across regions. Absent commitment, the central government may be induced to bailout the regional government in order to smooth consumption and distortionary taxes across the regions. We characterize the conditions under which bailouts occur and their welfare implications. The gains to creating a federation are higher when the (government spending) shocks across regions are negatively correlated and volatile. We use these insights to comment on actual fiscal relations in three quite different federations: the US, the European Union and Argentina.

Capital Accumulation and Annuities in an Adverse Selection Economy

This paper suggests that adverse selection problems in competitive annuity markets can generate quantity constrained equilibria in which some agents whose length of lifetime is uncertain find it advantageous to accumulate capital privately. This occurs despite the higher rates of return on annuities. The welfare properties of these allocations are analyzed. It is shown that the level of capital accumulation is excessive in a Paretian sense. Policies which eliminate this inefficiency are discussed.

Is it is or is it ain't my obligation? Regional debt in a fiscal federation

This paper studies the repayment of regional debt in a multiregion economy with a central authority: Who pays the obligation issued by a region? With commitment, a central government will use its taxation power to smooth distortionary taxes across regions. Absent commitment, the central government may be induced to bail out the regional government in order to smooth consumption and distortionary taxes across the regions. We characterize the conditions under which bailouts occur and their welfare implications. The gains to creating a federation are higher when the (government spending) shocks across regions are negatively correlated and volatile. We use these insights to comment on actual fiscal relations in three quite different federations: the U.S., the European Union and Argentina.Taxation

Insulation Impossible : Fiscal Spillovers in a Monetary Union

This paper studies the effects of monetary policy rules in a fiscal federation, such as the European Union. The focus of the analysis is the interaction between the fiscal policy of member countries (regions) and the monetary authority. Each of the countries structures its fiscal policy (spending and taxes) with the interests of its citizens in mind. Ricardian equivalence does not hold due to the presence of monetary frictions, modeled here as reserve requirements. When capital markets art integrated, the fiscal policy of one country influences equilibrium wages and interest rates. Under certain rules, monetary policy may respond to the price variations induced by regional fiscal policies. Depending on the type of rule it adopts, interventions by the monetary authority affect the magnitude and nature of the spillover from regional fiscal policy.Monetary union, inflation tax, seigniorage, monetary rules, public debt.

Is it is or is it Ain't my Obligation? Regional Debt in Monetary Unions

This paper studies the implications of the circulation of interest bearing regional debt in a monetary union. Does the circulation of this debt have the same monetary implications as the printing of money by a central government? Or are the obligations of this debt simply backed by future taxation with no inflationary consequences? We argue here that both outcomes can arise in equilibrium. In the model economy we consider there are multiple equilibria which reflect the perceptions of agents regarding the manner in which the debt obligations will be met. In one equilibrium, termed Ricardian, the future obligations are met with taxation by a regional government while in the other, termed Monetization, the central bank is induced to print money to finance the region's obligations. The multiplicity of equilibria reflects a commitment problem of the central bank. A key indicator of the selected equilibrium is the distribution of the holdings of the regional debt. We use the model to assess the impact of policy measures, such as fiscal restrictions, within a monetary union.

Phase Transitions in Gravitational Allocation

Given a Poisson point process of unit masses (``stars'') in dimension d>=3, Newtonian gravity partitions space into domains of attraction (cells) of equal volume. In earlier work, we showed the diameters of these cells have exponential tails. Here we analyze the quantitative geometry of the cells and show that their large deviations occur at the stretched-exponential scale. More precisely, the probability that mass exp(-R^gamma) in a cell travels distance R decays like exp(-R^f_d(gamma)) where we identify the functions f_d exactly. These functions are piecewise smooth and the discontinuities of f_d' represent phase transitions. In dimension d=3, the large deviation is due to a ``distant attracting galaxy'' but a phase transition occurs when f_3(gamma)=1 (at that point, the fluctuations due to individual stars dominate). When d>=5, the large deviation is due to a thin tube (a ``wormhole'') along which the star density increases monotonically, until the point f_d(gamma)=1 (where again fluctuations due to individual stars dominate). In dimension 4 we find a double phase transition, where the transition between low-dimensional behavior (attracting galaxy) and high-dimensional behavior (wormhole) occurs at gamma=4/3. As consequences, we determine the tail behavior of the distance from a star to a uniform point in its cell, and prove a sharp lower bound for the tail probability of the cell's diameter, matching our earlier upper bound.Comment: 66 pages. 9 figure