Unequivocal Majority and Maskin-Monotonicity

The unequivocal majority of a social choice rule F is the minimum number of agents that must agree on their best alternative in order to guarantee that this alternative is the only one prescribed by F. If the unequivocal majority of F is larger than the minimum possible value, then some of the alternatives prescribed by F are undesirable (there exists a different alternative which is the most preferred by more than 50% of the agents). Moreover, the larger the unequivocal majority of F, the worse these alternatives are (since the proportion of agents that prefer the same different alternative increases). We show that the smallest unequivocal majority compatible with Maskin-monotonicity is n-((n-1)/m), where n=3 is the number of agents and m=3 is the number of alternatives. This value represents no less than 66.6% of the population.Maskin-monotonicity; Majority; Condorcet winner

Entrepreneurship and Quality of Institutions

Over the last few years we have observed a prominent flourishing of empirical studies on the determinants of new business creation and its effect on the economy. The present study focuses on an important determinant of entrepreneurship: the quality of institutions. This paper is an empirical exploratory work that has the objective of uncovering the relationships between entrepreneurial dynamics and different variables related to the quality of government institutions, with an emphasis on developing countries. The study is based on the panel data of 60 countries that participated in the Global Entrepreneurship Monitor (GEM) project. The results indicate that the quality of institutions is a relevant factor for the distribution and type of entrepreneurial activities. Some implications for public policy are discussed.entrepreneurship, government institutions, Global Entrepreneurship Monitor

Towards a Better Understanding of the Semigroup Tree

In this paper we elaborate on the structure of the semigroup tree and the regularities on the number of descendants of each node observed earlier. These regularites admit two different types of behavior and in this work we investigate which of the two types takes place in particular for well-known classes of semigroups. Also we study the question of what kind of chains appear in the tree and characterize the properties (like being (in)finite) thereof. We conclude with some thoughts that show how this study of the semigroup tree may help in solving the conjecture of Fibonacci-like behavior of the number of semigroups with given genus.Comment: 17 pages, 2 figure

Size of Isospin Breaking in Charged K(L4) Decay

We evaluate the size of isospin breaking corrections to form factors $f$ and $g$ of the $K_{\ell 4}$ decay process $K^+\to\pi^+\pi^-\ell^+\nu_{\ell}$ which is actually measured by the extended NA48 setup at CERN. We found that, keeping apart the effect of Coulomb interaction, isospin breaking does not affect modules. This is due to the cancelation between corrections of electromagnetic origin and those generated by the difference between up and down quark masses. On the other hand, electromagnetism affects considerably phases if the infrared divergence is dropped out using a minimal subtraction scheme. Consequently, the greatest care must be taken in the extraction of $\pi\pi$ phase shifts from experiment.Comment: 29 pages, LaTeX, 7 postscript figure

Semileptonic decays of charmed mesons in the effective action of QCD

Within the framework of phenomenological Lagrangians we construct the effective action of QCD relevant for the study of semileptonic decays of charmed mesons. Hence we evaluate the form factors of D -> P(0^-) l^+ nu_l at leading order in the 1/N_C expansion and, by demanding their QCD-ruled asymptotic behaviour, we constrain the couplings of the Lagrangian. The features of the model-independent parameterization of form factors provided and their relevance for the analysis of experimental data are pointed out.Comment: 1+24 pages, 1 figure. Updated version. Conclusions unchanged. Accepted for publication in The European Physical Journal

Kl4K_{l4} at two-loops and CHPT predictions for ππ\pi\pi-scattering

We present the results from our two-loop calculations of masses, decay-constants, vacuum-expectation-values and the $K_{\ell4}$ form-factors in three-flavour Chiral Perturbation Theory (CHPT). We use this to fit the $L_i^r$ to two-loops and discuss the ensuing predictions for $\pi\pi$-threshold parameters.Comment: Talk presented at Chiral Dynamics 2000, Jefferson Lab, Newport News, Virginia, USA, July 17-22, 2000, 2