Chern slopes of simply connected complex surfaces of general type are dense in [2,3]

We prove that for any number $r$ in $[2,3]$, there are spin (resp. non-spin minimal) simply connected complex surfaces of general type $X$ with $c_1^2(X)/c_2(X)$ arbitrarily close to $r$. In particular, this shows the existence of simply connected surfaces of general type arbitrarily close to the Bogomolov-Miyaoka-Yau line. In addition, we prove that for any $r \in [1,3]$ and any integer $q\geq 0$, there are minimal complex surfaces of general type $X$ with $c_1^2(X)/c_2(X)$ arbitrarily close to $r$, and $\pi_1(X)$ isomorphic to the fundamental group of a compact Riemann surface of genus $q$.Comment: 20 pages. Final versio

Distributive and Regional Effects of Monopoly Power

This paper estimates the distributive and regional effects of firms with market power in the case of Mexico. It presents evidence that the welfare losses due to the exercise of monopoly power are not only significant, but also regressive. Moreover, the losses are different for the urban and rural sectors, as well as for each of the states of Mexico, being the inhabitants of the poorest ones the most affected by firms with market power.monopoly, Cournot oligopoly, distributive effects, regional effects, income distribution, goods markets, Mexico

Omnibus Tests for Multivariate Normality of Observations and Residuals

This paper provides omnibus tests for multivariate normality of both observations and residuals. They are derived by considering as the alternatives to the multivariate normal a class of maximum-entropy distributions studied elsewhere by the author. The tests, being Lagrange multiplier statistics, have optimum local asymptotic power among those alternatives. Furthermore, they coincide in the univariate case with the popular Jarque-Bera test for normality. They also include as special cases several multivariate tests available in the literature. Finally, the paper also suggests simple adjustments that can significantly improve the power of the tests in the case of small and medium size samples, even for the univariate case.test, multivariate normality, maximum entropy

Welfare consequences of a recent tax reform in Mexico

This paper evaluates the indirect tax reforms that took place in México in 1995 and 1998, focusing on their impact on welfare at the household and social levels. The empirical analysis is based on the estimation of an Almost Ideal Demand system, using its correct nonlinear version and by means of the generalized method of moments.tax reform, indirect tax, Mexico, reforma tributaria, impuestos indirectos

The Ahmad-Stern approach revisited: Variants and an application to Mexico

This paper extends the methodology first proposed by Ahmad and Stern for the design of tax reforms that are optimal at the margin. The extension centers on a sharper approximation of welfare measures. The original approach and its variant are illustrated in the case of the current Mexican tax system.Ahmad-Stern approach, marginal tax reform

Testing for Zipf’s Law: A Common Pitfall

It is noted that the regression procedure commonly used when testing for Zipf’s law is erroneous.Zipf’s law, rank-size

Resuelve: A Gauss program for solving computable general equilibrium and disequilibrium models

This paper describes a GAUSS program that can be used, among other things, to find equilibria for computable general equilibrium models, and fix price equilibria for general non Walrasian models. Simple applications for those two cases, as well as for linear and quadratic programming, are also provided.computable general equilibrium, disequilibrium, fix price equilibria, desequilibrio, precios rígidos