Inner and Outer Rounding of Boolean Operations on Lattice Polygonal Regions

Robustness problems due to the substitution of the exact computation on real numbers by the rounded floating point arithmetic are often an obstacle to obtain practical implementation of geometric algorithms. If the adoption of the --exact computation paradigm--[Yap et Dube] gives a satisfactory solution to this kind of problems for purely combinatorial algorithms, this solution does not allow to solve in practice the case of algorithms that cascade the construction of new geometric objects. In this report, we consider the problem of rounding the intersection of two polygonal regions onto the integer lattice with inclusion properties. Namely, given two polygonal regions A and B having their vertices on the integer lattice, the inner and outer rounding modes construct two polygonal regions with integer vertices which respectively is included and contains the true intersection. We also prove interesting results on the Hausdorff distance, the size and the convexity of these polygonal regions

Dynamic Quantum Logic for Quantum Programs

We present a way to apply quantum logic to the study of quantum programs. This is made possible by using an extension of the usual propositional language in order to make transformations performed on the system appear explicitly. This way, the evolution of the system becomes part of the logical study. We show how both unitary operations and two-valued measurements can be included in this formalism and can thus be handled logically.Comment: Submitted to the International Journal of Quantum Informatio

Processing and electrical characterization of a unidirectional CFRP composite filled with double walled carbon nanotubes

Carbon nanotubes represent new emergent multifunctional materials that have potential applications for structural and electrically conductive composites. In the current paper we present a suitable technique for the integration of Double Walled Carbon Nanotubes (DWCNTs) in a unidirectional Carbon Fiber Reinforced Polymer (CFRP) with high volume content of carbon fiber. We showed that the electrical conductivity of the laminates versus temperature follows a non-linear variation which can be well described by the Fluctuation-Induced Tunneling Conduction (FITC) model. The parameters of this model for CFRP/ DWCNTs and CFRP without DWCNTs were determined using best fit curves of the experimental data. This study has shown that DWCNTs have strong influence in the conductivity through laminate thickness. However, there are no significant effects on the electrical conductivity measured in the other two principle directions of the composite laminate. Furthermore, it was found that electron conduction mechanism of carbon fibers is dominated by the FITC

Rosca Participation in Benin : a Commitment Issue

In the light of first-hand data from a Beninese urban household survey in Cotonou, we investigate several motives aiming to explain participation in Rotating Savings and Credit ASsociations. We provide empirical findings which indicate that individuals use their participation in a rosca as a device to discipline themselves to save money and commit against problems of self-control.ROSCA, self-control, Benin, Intra-Household Allocation, Saving, Household Survey, Development Finance

The environmental resource curse hypothesis: the forest case

The resource curse hypothesis relies on the resource-rich countries tendency to grow slower than resource-poor countries. Focusing on forest issues, this paper extends the resource curse hypothesis to environmental degradation: how do forest endowment and forest harvesting affect deforestation? Our empirical results show that countries with important forest cover and forestry sectors seem to deforest more than others, which supports the hypothesis of an environmental resource curse. Moreover, countries implied in important timber certification processes have lower deforestation levels.resource curse, tropical forest, deforestation

A Broad-Spectrum Computational Approach for Market Efficiency

The Efficient Market Hypothesis (EMH) is one of the most investigated questions in Finance. Nevertheless, it is still a puzzle, despite the enormous amount of research it has provoked. For instance, it is still discussed that market cannot be outperformed in the long run (Detry and Gregoire, 2001), persistent market anomalies cannot be easily explained in this theoretical framework (Shiller, 2003) and some talented hedge-fund managers keep earning excess risk-adjusted rates of returns regularly. We concentrate in this paper on the weak form of efficiency(Fama, 1970). We focus on the efficacity of simple technical trading rules, following a large research stream presented in Park and Irwin (2004). Nevertheless, we depart from previous works in many ways : we first have a large population of technical investment rules (more than 260.000) exploiting real-world data to manage a financial portfolio. Very few researches have used such a large amount of calculus to examine the EMH. Our experimental design allows for strategy selection based on past absolute performance. We take into account the data-snooping risk, which is an unavoidable problem in such broad-spectrum researches, using a rigorous Bootstrap Reality Check procedure. While market inefficiencies, after including transaction costs, cannot clearly be successfully exploited, our experiments present troubling outcomes inviting close re-consideration of the weak-form EMH.efficient market hypothesis, large scale simulations, bootstrap