Orders of Nikshych's Hopf algebra

Let $p$ be an odd prime number and $K$ a number field having a primitive $p$-th root of unity $\zeta.$ We prove that Nikshych's non-group theoretical Hopf algebra $H_p$, which is defined over $\mathbb{Q}(\zeta)$, admits a Hopf order over the ring of integers $\mathcal{O}_K$ if and only if there is an ideal $I$ of $\mathcal{O}_K$ such that $I^{2(p-1)} = (p)$. This condition does not hold in a cyclotomic field. Hence this gives an example of a semisimple Hopf algebra over a number field not admitting a Hopf order over any cyclotomic ring of integers. Moreover, we show that, when a Hopf order over $\mathcal{O}_K$ exists, it is unique and we describe it explicitly.Comment: 33 pages. Major changes in the presentatio

Sovereign Default, Terms of Trade and Interest Rates in Emerging Markets

Emerging economies tend to experience larger fluctuations in their terms of trade, countercyclical interest rates and more default episodes than developed countries. These structural features might suggest a relevant role for world prices in driving country spreads. This paper studies the role of terms of trade shocks in inducing output fluctuations and countercyclical spreads using a stochastic dynamic general equilibrium model of a small open economy. The model predicts that default incentives and default premia are higher in recessions, as observed in the data. In a quantitative exercise, the model matches various features of emerging economies and can account for the dynamics of default episodes in these markets.Default, Terms of Trade, Sovereign Debt

On two finiteness conditions for Hopf algebras with nonzero integral

A Hopf algebra is co-Frobenius when it has a nonzero integral. It is proved that the composition length of the indecomposable injective comodules over a co-Frobenius Hopf algebra is bounded. As a consequence, the coradical filtration of a co-Frobenius Hopf algebra is finite; this confirms a conjecture by Sorin D\u{a}sc\u{a}lescu and the first author. The proof is of categorical nature and the same result is obtained for Frobenius tensor categories of subexponential growth. A family of co-Frobenius Hopf algebras that are not of finite type over their Hopf socles is constructed, answering so in the negative another question by the same authors.Comment: Minor changes. Final version, to appear in Ann. Sc. Norm. Super. Pisa Cl. Sci. (5); 33 page

Sovereign Default, Interest Rates and Political Uncertainty in Emerging Markets

Emerging economies tend to experience larger political uncertainty and more default episodes than developed countries. This paper studies the effect of political uncertainty on sovereign default and interest rate spreads in emerging markets. The paper develops a quantitative model of sovereign debt and default under political uncertainty in a small open economy. Consistent with empirical evidence, the quantitative analysis shows that higher levels of political uncertainty significantly raise the default frequency and both the level and volatility of the spreads. When parties borrow from international credit markets, the presence of political uncertainty induces a short-sight behavior in politicians.Default, Sovereign Debt, Political Risk

Fiscal Policy and Default Risk in Emerging Markets.

Emerging economies usually experience procyclical public expenditures, tax rates and private consumption, countercyclical default risk, interest rate spreads and current account and higher volatility in consumption than in output. In this article we develop a dynamic stochastic equilibrium model of a small open economy with endogenous fiscal policy, endogenous default risk and country interest rate spreads in an incomplete credit markets framework that rationalizes these empirical findings.Procyclical fiscal policy, Sovereign default