Market free lunch and large financial markets

The main result of the paper is a version of the fundamental theorem of asset pricing (FTAP) for large financial markets based on an asymptotic concept of no market free lunch for monotone concave preferences. The proof uses methods from the theory of Orlicz spaces. Moreover, various notions of no asymptotic arbitrage are characterized in terms of no asymptotic market free lunch; the difference lies in the set of utilities. In particular, it is shown directly that no asymptotic market free lunch with respect to monotone concave utilities is equivalent to no asymptotic free lunch. In principle, the paper can be seen as the large financial market analogue of [Math. Finance 14 (2004) 351--357] and [Math. Finance 16 (2006) 583--588].Comment: Published at http://dx.doi.org/10.1214/105051606000000484 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

A fundamental theorem of asset pricing for continuous time large financial markets in a two filtration setting

We present a version of the fundamental theorem of asset pricing (FTAP) for continuous time large financial markets with two filtrations in an $L^p$-setting for $1 \leq p < \infty$. This extends the results of Yuri Kabanov and Christophe Stricker \cite{KS:06} to continuous time and to a large financial market setting, however, still preserving the simplicity of the discrete time setting. On the other hand it generalizes Stricker's $L^p$-version of FTAP \cite{S:90} towards a setting with two filtrations. We do neither assume that price processes are semi-martigales, (and it does not follow due to trading with respect to the \emph{smaller} filtration) nor that price processes have any path properties, neither any other particular property of the two filtrations in question, nor admissibility of portfolio wealth processes, but we rather go for a completely general (and realistic) result, where trading strategies are just predictable with respect to a smaller filtration than the one generated by the price processes. Applications range from modeling trading with delayed information, trading on different time grids, dealing with inaccurate price information, and randomization approaches to uncertainty

Asymptotic proportion of arbitrage points in fractional binary markets

A fractional binary market is an approximating sequence of binary models for the fractional Black-Scholes model, which Sottinen constructed by giving an analogue of the Donsker's theorem. In a binary market the arbitrage condition can be expressed as a condition on the nodes of a binary tree. We call "arbitrage points" the points in the binary tree which verify such an arbitrage condition and "arbitrage paths" the paths in the binary tree which cross at least one arbitrage point. Using this terminology, a binary market admits arbitrage if and only if there is at least one arbitrage point in the binary tree or equivalently if there is at least one arbitrage path. Following the lines of Sottinen, who showed that the arbitrage persists in the fractional binary market, we further prove that starting from any point in the tree, we can reach an arbitrage point. This implies that, in the limit, there is an infinite number of arbitrage points. Next, we provide an in-depth analysis of the asymptotic proportion of arbitrage points at asymptotic levels and of arbitrage paths in the fractional binary market. All these results are obtained by studying a rescaled disturbed random walk. We moreover show that, when $H$ is close to $1$, with probability $1$ a path in the binary tree crosses an infinite number of arbitrage points. In particular, for such $H$, the asymptotic proportion of arbitrage paths is equal to $1$

More bits - more bucks? Measuring the impact of broadband internet on firm performance

The paper provides empirical evidence for the causal impact of broadband Internet on the economic performance of German firms. Performance is measured in terms of labour productivity and realised process and product innovations. The analysis refers to the early phase of DSL expansion in Germany from 2001 to 2003, when roughly 60 percent of the German firms already used broadband Internet. Identification relies on instrumental variable estimation taking advantage of information on the availability of DSL broadband at the postal code level. The results show that broadband Internet has no impact on firms' labour productivity whereas it exhibits a positive and significant impact on their innovation activity. --labour productivity,innovation,broadband Internet

More bits more bucks? : Measuring the impact of broadband internet on firm performance

The paper provides empirical evidence for the causal impact of broadband Internet on the economic performance of German firms. Performance is measured in terms of labour productivity and realised process and product innovations. The analysis refers to the early phase of DSL expansion in Germany from 2001 to 2003, when roughly 60 percent of the German firms already used broadband Internet. Identification relies on instrumental variable estimation taking advantage of information on the availability of DSL broadband at the postal code level. The results show that broadband Internet has no impact on firms' labour productivity whereas it exhibits a positive and significant impact on their innovation activity

La teoría en la práctica de la escritura de ficción

El objetivo del trabajo es estudiar la incidencia de la teoría -el análisis literario propuesto por la narratología (Gerard Genette 1962,1966,1969,1972)- en un taller de escritura, reflexionar sobre los alcances y las limitaciones de un enfoque descriptivo de los hechos literarios en la práctica de la escritura de ficción como también sobre la necesidad de abordarlos desde un enfoque pluridisciplinario. Para ello se analizará la experiencia didáctica que se realiza en la materia Taller de Expresión I (Ciencias de la Comunicación), que fuera diseñada por Gloria Pampillo y Maite Alvarado con el propósito de promover las potencialidades cognitivas de la escritura