Model Checker Execution Reports

Software model checking constitutes an undecidable problem and, as such, even an ideal tool will in some cases fail to give a conclusive answer. In practice, software model checkers fail often and usually do not provide any information on what was effectively checked. The purpose of this work is to provide a conceptual framing to extend software model checkers in a way that allows users to access information about incomplete checks. We characterize the information that model checkers themselves can provide, in terms of analyzed traces, i.e. sequences of statements, and safe cones, and present the notion of execution reports, which we also formalize. We instantiate these concepts for a family of techniques based on Abstract Reachability Trees and implement the approach using the software model checker CPAchecker. We evaluate our approach empirically and provide examples to illustrate the execution reports produced and the information that can be extracted

On Verifying Resource Contracts using Code Contracts

In this paper we present an approach to check resource consumption contracts using an off-the-shelf static analyzer. We propose a set of annotations to support resource usage specifications, in particular, dynamic memory consumption constraints. Since dynamic memory may be recycled by a memory manager, the consumption of this resource is not monotone. The specification language can express both memory consumption and lifetime properties in a modular fashion. We develop a proof-of-concept implementation by extending Code Contracts' specification language. To verify the correctness of these annotations we rely on the Code Contracts static verifier and a points-to analysis. We also briefly discuss possible extensions of our approach to deal with non-linear expressions.Comment: In Proceedings LAFM 2013, arXiv:1401.056

Do foreign portfolio flows increase risk in emerging stock markets? Evidence from six Latin American countries 1999 -2008

Foreign portfolio flows have been blamed for causing instability in emerging markets, especially during financial crises. This study measured the effect of foreign capital flows on volatility and exposure to world market risk in the six largest Latin American stock markets: Argentina, Brazil, Colombia, Chile, Mexico and Peru, for around 10 years including the 2008’s World financial crisis. This will test whether these flows cause instability for those markets and increase their exposure to international stock market returns. A proprietary database, from Emerging Portoflio.com and time series models, both univariate (ARCH - GARCH) and multivariate (VAR), are used to estimate the effect foreign portfolio flows on the risk variables and the causality of these effects. We found no strong evidence to support the hypothesis that foreign flows cause instability in the Latin American stock markets, in spite of some evidence of causing price pressure. Instead, the evidence points to a strong dependence of market returns on international stock and foreign exchange markets, both in means and in volatility, instrumental to transmit crisis to those markets

Do foreign portfolio flows increase risk in emerging stock markets? Evidence from six Latin American countries

Foreign portfolio flows have been blamed for causing instability in emerging markets, especially during financial crises. This study measured the effect of foreign capital flows on volatility and exposure to world market risk in the six largest Latin American stock markets: Argentina, Brazil, Colombia, Chile, Mexico and Peru, for around 10 years including the 2008 World financial crisis. This will test whether these flows cause instability for those markets and increase their exposure to international stock market returns. A proprietary database, from Emerging Portoflio.com and time series models, both univariate (ARCH-GARCH) and multivariate (VAR), are used to estimate the effect foreign portfolio flows on the risk variables and the causality of these effects. We found no strong evidence to support the hypothesis that foreign flows cause instability in the Latin American stock markets, in spite of some evidence of causing price pressure. Instead, the evidence points to a strong dependence of market returns on international stock and foreign exchange markets, both in means and in volatility, instrumental to transmit crisis to those markets

Indicadores financeiros como poderoso instrumento para prever insolvência. Um estudo usando o algoritmo boosting em empresas colombianas

This study is motivated by the importance of accurately predicting insolvency before it happens. The paper aims to develop an insolvency prediction model for Colombian firms with one, two and three years of anticipation through financial ratios, keeping sample structures and taking into account insolvency-related regulation. This research contributes to the literature because unlike many studies, it takes legislation into account, explains the different types of financial ratios, and uses boosting algorithms without biasing the sample. Data from 11,812 Colombian companies covering the period 2012-2016 was used. The results show accuracy above 70% for insolvency predic­tion with one, two and three years of anticipation.Esta investigación es motivada por la importancia de tener una buena predicción de la insolvencia con anticipación. El objetivo de este artículo es desarrollar un modelo predictivo para las empresas colombianas con uno, dos y tres años de anticipación usando indicadores financieros, conservando la estructura de la muestra original y teniendo en cuenta la regulación sobre insolvencia. Este artículo contribuye a la literatura ya que, a diferencia de los estudios tradicionales, se tienen en cuenta aspectos como la legislación, se explican los diferentes tipos de indicadores financieros y se utiliza el algoritmo boosting sin sesgar la muestra inicial. Para el desarrollo de este estudio se consideró una muestra de 11.812 empresas colombianas durante el periodo 2012-2016. Los resultados muestran una precisión superior al 70% en la predicción de la insolvencia con uno, dos y tres años de anticipación.Esta pesquisa é motivada pela importância de ter uma boa previsão de insolvência com antecedência. O objetivo deste artigo é desenvolver um modelo preditivo para as empresas colombianas com um, dois e três anos de antecedência, utilizando indicadores financeiros, preser­vando a estrutura original da amostra e levando em consideração o regulamento de insolvência. Este artigo contribui com a literatura, pois, diferentemente dos estudos tradicionais, são levados em consideração aspectos como legislação, explicando os diferentes tipos de indica­dores financeiros, e o algoritmo boosting é utilizado sem influenciar a amostra inicial. Para o desenvolvimento deste estudo, considerou-se uma amostra de 11.812 empresas colombianas durante o período 2012-2016. Os resultados mostram uma precisão superior a 70% na previsão da insolvência com um, dois e três anos de antecedência

Symmetries of Lagrangian fibrations

We construct fiber-preserving anti-symplectic involutions for a large class of symplectic manifolds with Lagrangian torus fibrations. In particular, we treat the K3 surface and the quintic threefold. We interpret our results as corroboration of the view that in homological mirror symmetry, an anti-symplectic involution is the mirror of duality. In the same setting, we construct fiber-preserving symplectomorphisms that can be interpreted as the mirror to twisting by a holomorphic line bundle.Comment: 45 page

Desarrollo de un sistema de recogida de datos en Facebook aplicando gamificación

El surgimiento del Big Data unido al auge de las redes sociales en los últimos años ha propiciado que éstas almacenen cada vez más datos de los usuarios, en un intento de rentabilizar su modelo de negocio, explotándolos principalmente a través de la publicidad dirigida. Facebook se encuentra a la cabeza en esta carrera por los datos, almacenando información de 1.44 billones de usuarios (datos personales, gustos, relaciones, etc.). Con este creciente ecosistema surgen nuevas oportunidades para el área de la minería de datos, que podría servirse de este tipo de conjuntos para, por ejemplo, desarrollar sistemas de recomendación. Por otro lado, a la par que nuevas oportunidades, surgen nuevos desafíos, entre ellos el de cómo conseguir acceso a estos datos. La privacidad se ha convertido en una prioridad para los usuarios de las redes sociales, por lo que normalmente sólo podremos acceder a aquellos datos que los propios usuarios elijan compartir con nosotros. El objetivo de este proyecto era estudiar la posibilidad de aplicar gamificación a una aplicación en Facebook para conseguir recoger los datos del máximo número posible de usuarios. Entendemos por gamificación la extrapolación de mecánicas propias de los videojuegos a otros contextos. En nuestro caso, se buscó especialmente potenciar la componente social para crear un efecto viral en la difusión de la aplicación. En este documento se describe detalladamente cómo se analizó, diseñó, implementó, probó y monitorizó una aplicación que recoge datos de Facebook aplicando mecánicas de gamificación. Para reducir el dominio de la aplicación, se decidió que ésta analizaría los gustos musicales de los usuarios, mostrándole unos resultados personalizados y permitiendo comparar sus resultados con los de sus amigos. La aplicación fue publicada y a lo largo de un mes logró recoger datos de 170 usuarios, incluyendo sus “Me gusta” y sus relaciones de amistad. Como resultado de este proyecto se publicó el código de la aplicación en un repositorio de GitHub y se cedió el conjunto de datos recogidos al grupo de investigación IRG (1) de la Universidad Autónoma de Madrid.The rise of Big Data in addition to the growth of online social networks in recent years has made them store more and more user data in an attempt to monetize their business model, exploiting it mainly through targeted advertising. Facebook is ahead in this race for the data, storing information of 1.44 billion users (personal data, likes, relationships, etc.). With this growing ecosystem new opportunities appear for the area of data mining, which could use this kind of data sets to, for instance, develop recommendation systems. On the other hand, new opportunities emerge together with new challenges, including how to access these data. Privacy has become a priority for users of social networks, so normally we will be able to access only the data that the users choose to share with us. The main goal of this project was to study the possibility of applying gamification to a Facebook application in order to collect data of the maximum possible amount of users. Gamification is the act of extrapolating gaming mechanics to other contexts. In our case, it sought specifically to improve the social component to create a viral effect in the spreading of the application. This document describes in detail how we analyzed, designed, implemented, tested and monitored an application that collects data from Facebook applying gamification mechanics. To reduce the application domain, it was decided that the application would analyze the musical likes of the users, showing some personalized results and allowing them to compare their results with their friend’s ones. The application was published and managed to collect data from 170 users over the course of a month, including their likes and their friendships. As a result of this project the application code was published in a GitHub repository and the yielded data set was transferred to the IRG (1) research group of the Autonomous University of Madrid

Capital relacional y construcción de ventajas competitivas, caso de estudio en la empresa Induservi SAS

El análisis del Capital Intelectual para la generación de ventaja competitiva se ha incorporado en el ámbito académico y en la gestión administrativa en las últimas décadas, debido a la generalidad aceptada de la expresión sociedad del conocimiento y economía basada en el conocimiento, en la cual los activos intangibles han pasado a tomar un papel preponderante en la creación de valor por parte de las organizaciones. El propósito del presente trabajo consiste en abordar el análisis del desarrollo teórico del capital intelectual alcanzado desde su aparición, y sus perspectivas actuales; así como la observación práctica de la medición de uno de sus componentes, el capital relacional, en una empresa del sector manufacturero de la ciudad de ManizalesAbstract : Relational capital and construction of competitive advantages, case of study in the Company Induservi SAS Analysis of Intellectual Capital for the generation of competitive advantage has been incorporated into the Academic and administrative management in the last decades, due to the general acceptance of the term knowledge society and knowledge-based economy, in which intangible assets have gone to take a leading role in creating value for the organizations. The purpose of this paper is to address the analysis of the theoretical development of intellectual capital achieved since its inception, and its current prospects; practical observation and measurement of one component, the relational capital in a company for the manufacturing sector of the city of ManizalesMaestrí