An explicit universal cycle for the (n-1)-permutations of an n-set

We show how to construct an explicit Hamilton cycle in the directed Cayley graph Cay({\sigma_n, sigma_{n-1}} : \mathbb{S}_n), where \sigma_k = (1 2 >... k). The existence of such cycles was shown by Jackson (Discrete Mathematics, 149 (1996) 123-129) but the proof only shows that a certain directed graph is Eulerian, and Knuth (Volume 4 Fascicle 2, Generating All Tuples and Permutations (2005)) asks for an explicit construction. We show that a simple recursion describes our Hamilton cycle and that the cycle can be generated by an iterative algorithm that uses O(n) space. Moreover, the algorithm produces each successive edge of the cycle in constant time; such algorithms are said to be loopless

Boom-Bust Cycles in Middle Income Countries: Facts and Explanation

In this paper we characterize empirically the comovements of macro variables typically observed in middle income countries, as well as the boom-bust cycle that has been observed during the last two decades. We find that many countries that have liberalized their financial markets, have witnessed the development of lending booms. Most of the time the boom gradually decelerates, but sometimes the boom ends in twin currency and banking crises and is followed by a protracted credit crunch that outlives a short-lived recession. We also find that during lending booms there is a real exchange rate appreciation, and the nontradables (N) sector grows faster than the tradables (T) sector. Meanwhile, the opposite is true in the aftermath of crisis. We argue that these comovements are generated by the interaction of two characteristics of financing typical of middle income countries: risky currency mismatch and asymmetric financing opportunities across the N and T sectors Copyright 2002, International Monetary Fund

Credit Market Imperfections in Middle Income Countries

In this paper we document three credit market imperfections prevalent in middle income countries that can help to explain boom-bust cycles, as well as other macroeconomic patterns observed at higher frequencies across these countries. These imperfections are: the existence of financing constraints that affect mainly the nontradables sector, currency mismatch and guarantees that cover lenders against systemic crises. In MICs T-sector firms have access to international capital markets, while most N-firms are bank-dependent and are financially constrained. Systemic guarantees generate incentives for borrowers to take on insolvency risk by denominating debt in foreign currency. This currency mismatch makes movements in the real exchange rate – the relative price between N and T goods – the driving element in the amplification of shocks.

The Credit Channel in Middle Income Countries

With inflation under control in many in middle income countries (MICs), it is now swings in credit, investment and asset prices that affect these countries the most. In this paper we present a framework to analyze both theoretically and empirically how credit market shocks are propagated and amplified in MICs.The strength of the credit channel in our model derives from two key characteristics of MICs: (i)a sharp asymmetry across the tradables (T) sector and the more bank-dependent nontradables (N) sector; and (ii)a significant degree of currency mismatch in the N-sector. This makes movements in the real exchange rate the driving element in the amplification of shocks. The equilibrium imposes unambiguous contemporaneous linkages among key macroeconomic variables and allows us to derive structural VARs. Estimating these VARs using quarterly data for a group of MICs, we find evidence for a strong credit channel, for a balance sheet effect and for asymmetric sectorial responses. Our findings indicate that inflation targeting is not sufficient to guarantee economic stability, as such policy might overlook the development of lending booms and associated sectorial asymmetries.

The Credit Channel in Middle Income Countries

Credit market conditions play a key role in propagating shocks in middle income countries (MICs). In particular, shocks to the spread between domestic and international interest rates have a strong effect on GDP, and an even stronger effect on domestic credit. This strong credit channel is associated with a sharp sectorial asymmetry: the output of the bank-dependent nontradables (N) sector reacts more strongly than tradables (T) output. This asymmetry, in turn, is associated with a strong reaction of the real exchange rate --the relative price between N and T goods. We present a model that reconciles these facts and leads to a well specified estimation framework. From the equilibrium we derive structural VARs that allow us to identify shocks to credit market conditions and trace their effects on the economy. We estimate these structural VARs for a group of MICs and find evidence of a strong credit channel. We argue that at the heart of the MIC credit channel are a deep asymmetry in financing opportunities across N and T sectors, and a severe currency mismatch. This makes movements in the real exchange rate the driving element in the amplification of shocks. Finally, we show that the model's key assumptions are consistent with evidence gleaned from both firm level and aggregate data.

Boom-Bust Cycles in Middle Income Countries: Facts and Explanation

In this paper we characterize empirically the comovements of macro variables typically observed in middle income countries, as well as the boom-bust cycle' that has been observed during the last two decades. We find that many countries that have liberalized their financial markets, have witnessed the development of lending booms. Most of the time the boom gradually decelerates. But sometimes the boom ends in twin currency and banking crises, and is followed by a protracted credit crunch that outlives a short-lived recession. We also find that during lending booms there is a real appreciation and the nontradables (N) sector grows faster than the tradables (T) sector. Meanwhile, the opposite is true in the aftermath of crisis. We argue that these comovements are generated by the interaction of two characteristics of financing typical of middle income countries: risky currency mismatch and asymmetric financing opportunities across the N- and T-sectors.

Credit Market Imperfections in Middle Income Countries

In this paper we document three credit market imperfections prevalent in middle income countries that can help explain the boom-bust cycles as well as other macroeconomic patterns observed at higher frequencies across these countries. These imperfections are: the existence of financing constraints that affect mainly the nontradables sector, currency mismatch and systemic bailout guarantees.

Hopf structures on the multiplihedra

We investigate algebraic structures that can be placed on vertices of the multiplihedra, a family of polytopes originating in the study of higher categories and homotopy theory. Most compelling among these are two distinct structures of a Hopf module over the Loday-Ronco Hopf algebra.Comment: 24 pages, 112 .eps file

Crises and Growth: A Re-Evaluation

We address the question of whether growth and welfare can be higher in crisis prone economies. First, we show that there is a robust empirical link between per-capita GDP growth and negative skewness of credit growth across countries with active financial markets. That is, countries that have experienced occasional crises have grown on average faster than countries with smooth credit conditions. We then present a two-sector endogenous growth model in which financial crises can occur, and analyze the relationship between financial fragility and growth. The underlying credit market imperfections generate borrowing constraints, bottlenecks and low growth. We show that under certain conditions endogenous real exchange rate risk arises and firms find it optimal to take on credit risk in the form of currency mismatch. Along such a risky path average growth is higher, but self-fulfilling crises occur occasionally. Furthermore, we establish conditions under which the adoption of credit risk is welfare improving and brings the allocation nearer to the Pareto optimal level. The design of the model is motivated by several features of recent crises: credit risk in the form of foreign currency denominated debt; costly crises that generate firesales and widespread bankruptcies; and asymmetric sectorial responses, where the nontradables sector falls more than the tradables sector in the wake of crises.