Robust Exponential Worst Cases for Divide-et-Impera Algorithms for Parity Games

The McNaughton-Zielonka divide et impera algorithm is the simplest and most flexible approach available in the literature for determining the winner in a parity game. Despite its theoretical worst-case complexity and the negative reputation as a poorly effective algorithm in practice, it has been shown to rank among the best techniques for the solution of such games. Also, it proved to be resistant to a lower bound attack, even more than the strategy improvements approaches, and only recently a family of games on which the algorithm requires exponential time has been provided by Friedmann. An easy analysis of this family shows that a simple memoization technique can help the algorithm solve the family in polynomial time. The same result can also be achieved by exploiting an approach based on the dominion-decomposition techniques proposed in the literature. These observations raise the question whether a suitable combination of dynamic programming and game-decomposition techniques can improve on the exponential worst case of the original algorithm. In this paper we answer this question negatively, by providing a robustly exponential worst case, showing that no intertwining of the above mentioned techniques can help mitigating the exponential nature of the divide et impera approaches.Comment: In Proceedings GandALF 2017, arXiv:1709.0176

Expected fiscal policy and interest rates in open economy

This paper reconsiders the long term effect of fiscal policy on interest rates using a real-time dataset of macroeconomic and fiscal variables in a panel of 17 OECD countries over the period 1989-2009. We show that, after controlling for cross sectional dependence using a Factor Augmented Panel, interest rates are mostly related to global factors. Among domestic fiscal variables, the level of expected public debt mantains a positive correlation with interest rates, while among the global factors, the aggregate monetary and fiscal stance play a quantitatively sizeable role. We then analyze how impulses from the aggregate fiscal stance influence each country's interest rates. We find that these effects are modest in large economies and particularly strong in economies characterized by low initial financial integration, leading the way to a novel interpretation of the divergent behaviour of interest rates in the recent financial crisis

Surfing the Capital Waves: A sector-level examination of surges in FDI inflows

We examine episodes of large gross FDI inflows - surges - at the sectoral level between 1994 and 2009 for 95 emerging-market and industrial countries. We find that surges in the primary and manufacturing sectors are less cyclical and associated with lower macroeconomic volatility than surges in the business and finance sectors. The likely explanation for this result seems to be the expansion of credit associated with these flows. Turning to the determinants of surges, we find that global and contagion factors have a stronger effect in the services than the manufacturing sector; surges in financial sector FDI are particularly contagious in emerging market countries. With regard to domestic factors, we find that (i) high public debt reduces the likelihood of experiencing FDI surges in the manufacturing and trade/transport sector, that (ii) high growth pulls in FDI in the manufacturing sector and that (iii) privatization is strongly associated with FDI surges in the manufacturing and financial sector. Finally, we document a role for capital controls: they tend to increase the likelihood of FDI surges in the manufacturing, other services, and financial sector

Financial dollarization and currency substitution: an empirical study for Bolivia

The Bolivian puzzle is high and persistent financial dollarization notwithstanding deep macroeconomic stabilization that achieved stable and low inflation and the regulations encouraging domestic currency deposits. We analyze traditional and new approaches to explain dollarization in Bolivia. We first assess the currency substitution approach and then assess the empirical evidence for the financial dollarization approach. The results show that the macroeconomic variables capture only partially the phenomenon and a better assessment relies on other explanations such as the peso problem and the analysis of specific characteristics of the financial markets in Bolivia

Fiscal policy, interest rates and risk premia in open economy

This paper reconsiders the effects of fiscal policy on long-term interest rates and sovereign spreads employing a Factor Augmented Panel (FAP) to control for the presence of common unobservable factors. We construct a real-time dataset of macroeconomic and fiscal variables for a panel of OECD countries for the period 1989-2009. We find that two global factors - the global monetary and fiscal policy stances - explain more than 60% of the variance in the long-term interest rates. The same two global factors play a relevant role also in explaining the variance of sovereign spreads, which in addition respond to global risk aversion. With respect to standard estimation techniques the use of the FAP reduces the importance of domestic fiscal variables in explaining long- term interest rates, while it emphasizes their importance in explaining sovereign spreads. Using the FAP framework we also analyse the cross-country differences in the propagation of a shock to global fiscal stance and global risk aversion. We find the effects of the former to be modest in large economies and strong in economies characterized by low financial integration and current account deficits. Changes in global risk aversion, instead, lead to higher spreads in countries with a high stock of public debt and weaker political institutions

Complementary Organic Logic Gates on Plastic Formed by Self-Aligned Transistors with Gravure and Inkjet Printed Dielectric and Semiconductors

Complementary organic field-effect transistors, inverters, NAND and NOR logic on plastic are demonstrated using a combination of nanoimprint lithography, self-alignment, gravure, and inkjet printing. Sub-micrometer channel lengths, electrode overlaps and sub-100 nm dielectrics are compared to photolithographically patterned equivalents, as are inkjet and gravure printed semiconductors