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A random intersection graph is constructed by assigning independently to each vertex a subset of a given set and drawing an edge between two vertices if and only if their respective subsets intersect. In this article a model is developed in which each vertex is given a random weight and vertices with larger weights are more likely to be assigned large subsets. The distribution of the degree of a given vertex is characterized and is shown to depend on the weight of the vertex. In particular, if the weight distribution is a power law, the degree distribution will be as well. Furthermore, an asymptotic expression for the clustering in the graph is derived. By tuning the parameters of the model, it is possible to generate a graph with arbitrary clustering, expected degree, andin the power-law casetail exponent. © 2009 Cambridge University Press.

In the last decades, there was a notable progress in solving the well-known Boolean satisfiability (Sat) problem, which can be witnessed by powerful Sat solvers. One of the reasons why these solvers are so fast are structural properties of instances that are utilized by the solver’s interna. This thesis deals with the well-studied structural property treewidth, which measures the closeness of an instance to being a tree. In fact, there are many problems parameterized by treewidth that are solvable in polynomial time in the instance size when parameterized by treewidth. In this work, we study advanced treewidth-based methods and tools for problems in knowledge representation and reasoning (KR). Thereby, we provide means to establish precise runtime results (upper bounds) for canonical problems relevant to KR. Then, we present a new type of problem reduction, which we call decomposition-guided (DG) that allows us to precisely monitor the treewidth when reducing from one problem to another problem. This new reduction type will be the basis for a long-open lower bound result for quantified Boolean formulas and allows us to design a new methodology for establishing runtime lower bounds for problems parameterized by treewidth. Finally, despite these lower bounds, we provide an efficient implementation of algorithms that adhere to treewidth. Our approach finds suitable abstractions of instances, which are subsequently refined in a recursive fashion, and it uses Sat solvers for solving subproblems. It turns out that our resulting solver is quite competitive for two canonical counting problems related to Sat. In den letzten Jahrzehnten konnte ein beachtlicher Fortschritt im Bereich der Aussagenlogik verzeichnet werden. Dieser äußerte sich dadurch, dass für das wichtigste Problem in diesem Bereich, genannt „Sat“, welches sich mit der Fragestellung befasst, ob eine gegebene aussagenlogische Formel erfüllbar ist oder nicht, überwältigend schnelle Computerprogramme („Solver“) entwickelt werden konnten. Interessanterweise liefern diese Solver eine beeindruckende Leistung, weil sie oft selbst Probleminstanzen mit mehreren Millionen von Variablen spielend leicht lösen können. Auf der anderen Seite jedoch glaubt man in der Wissenschaft weitgehend an die Exponentialzeithypothese (ETH), welche besagt, dass man im schlimmsten Fall für das Lösen einer Instanz in diesem Bereich exponentielle Laufzeit in der Anzahl der Variablen benötigt. Dieser vermeintliche Widerspruch ist noch immer nicht vollständig geklärt, denn wahrscheinlich gibt es viele ineinandergreifende Gründe für die Schnelligkeit aktueller Sat Solver. Einer dieser Gründe befasst sich weitgehend mit strukturellen Eigenschaften von Probleminstanzen, die wohl indirekt und intern von diesen Solvern ausgenützt werden. Diese Dissertation beschäftigt sich mit solchen strukturellen Eigenschaften, nämlich mit der sogenannten Baumweite. Die Baumweite ist sehr gut erforscht und versucht zu messen, wie groß der Abstand von Probleminstanzen zu Bäumen ist (Baumnähe). Allerdings ist dieser Parameter sehr generisch und bei Weitem nicht auf Problemstellungen der Aussagenlogik beschränkt. Tatsächlich gibt es viele weitere Probleme, die parametrisiert mit Baumweite in polynomieller Zeit gelöst werden können. Interessanterweise gibt es auch viele Probleme in der Wissensrepräsentation (KR), von denen man davon ausgeht, dass sie härter sind als das Problem Sat, die bei beschränkter Baumweite in polynomieller Zeit gelöst werden können. Ein prominentes Beispiel solcher Probleme ist das Problem QSat, welches sich für die Gültigkeit einer gegebenen quantifizierten, aussagenlogischen Formel (QBF), das sind aussagenlogische Formeln, wo gewisse Variablen existenziell bzw. universell quantifiziert werden können, befasst. Bemerkenswerterweise wird allerdings auch im Zusammenhang mit Baumweite, ähnlich zu Methoden der klassischen Komplexitätstheorie, die tatsächliche Komplexität (Härte) solcher Problemen quantifiziert, wo man die exakte Laufzeitabhängigkeit beim Problemlösen in der Baumweite (Stufe der Exponentialität) beschreibt. Diese Arbeit befasst sich mit fortgeschrittenen, Baumweite-basierenden Methoden und Werkzeugen für Probleme der Wissensrepräsentation und künstlichen Intelligenz (AI). Dabei präsentieren wir Methoden, um präzise Laufzeitresultate (obere Schranken) für prominente Fragmente der Antwortmengenprogrammierung (ASP), welche ein kanonisches Paradigma zum Lösen von Problemen der Wissensrepräsentation darstellt, zu erhalten. Unsere Resultate basieren auf dem Konzept der dynamischen Programmierung, die angeleitet durch eine sogenannte Baumzerlegung und ähnlich dem Prinzip „Teile-und-herrsche“ funktioniert. Solch eine Baumzerlegung ist eine konkrete, strukturelle Zerlegung einer Probleminstanz, die sich stark an der Baumweite orientiert. Des Weiteren präsentieren wir einen neuen Typ von Problemreduktion, den wir als „decomposition-guided (DG)“, also „zerlegungsangeleitet“, bezeichnen. Dieser Reduktionstyp erlaubt es, Baumweiteerhöhungen und -verringerungen während einer Problemreduktion von einem bestimmten Problem zu einem anderen Problem präzise zu untersuchen und zu kontrollieren. Zusätzlich ist dieser neue Reduktionstyp die Basis, um ein lange offen gebliebenes Resultat betreffend quantifizierter, aussagenlogischer Formeln zu zeigen. Tatsächlich sind wir damit in der Lage, präzise untere Schranken, unter der Annahme der Exponentialzeithypothese, für das Problem QSat bei beschränkter Baumweite zu zeigen. Genauer gesagt können wir mit diesem Konzept der DG Reduktionen zeigen, dass das Problem QSat, beschränkt auf Quantifizierungsrang ` und parametrisiert mit Baumweite k, im Allgemeinen nicht besser als in einer Laufzeit, die `-fach exponentiell in der Baumweite und polynomiell in der Instanzgröße ist1, lösen. Dieses Resultat hebt auf nicht-inkrementelle Weise ein bekanntes Ergebnis für Quantifizierungsrang 2 auf beliebige Quantifizierungsränge, allerdings impliziert es auch sehr viele weitere Konsequenzen. Das Resultat über die untere Schranke des Problems QSat erlaubt es, eine neue Methodologie zum Zeigen unterer Schranken einer Vielzahl von Problemen der Wissensrepräsentation und künstlichen Intelligenz, zu etablieren. In weiterer Konsequenz können wir damit auch zeigen, dass die oberen Schranken sowie die DG Reduktionen dieser Arbeit unter der Hypothese ETH „eng“ sind, d.h., sie können wahrscheinlich nicht mehr signifikant verbessert werden. Die Ergebnisse betreffend der unteren Schranken für QSat und die dazugehörige Methodologie konstituieren in gewisser Weise eine Hierarchie von über Baumweite parametrisierte Laufzeitklassen. Diese Laufzeitklassen können verwendet werden, um die Härte von Problemen für das Ausnützen von Baumweite zu quantifizieren und diese entsprechend ihrer Laufzeitabhängigkeit bezüglich Baumweite zu kategorisieren. Schlussendlich und trotz der genannten Resultate betreffend unterer Schranken sind wir im Stande, eine effiziente Implementierung von Algorithmen basierend auf dynamischer Programmierung, die entlang einer Baumzerlegung angeleitet wird, zur Verfügung zu stellen. Dabei funktioniert unser Ansatz dahingehend, indem er probiert, passende Abstraktionen von Instanzen zu finden, die dann im Endeffekt sukzessive und auf rekursive Art und Weise verfeinert und verbessert werden. Inspiriert durch die enorme Effizienz und Effektivität der Sat Solver, ist unsere Implementierung ein hybrider Ansatz, weil sie den starken Gebrauch von Sat Solvern zum Lösen diverser Subprobleme, die während der dynamischen Programmierung auftreten, pflegt. Dabei stellt sich heraus, dass der resultierende Solver unserer Implementierung im Bezug auf Effizienz beim Lösen von zwei kanonischen, Sat-verwandten Zählproblemen mit bestehenden Solvern locker mithalten kann. Tatsächlich sind wir im Stande, Instanzen, wo die oberen Schranken von Baumweite 260 übersteigen, zu lösen. Diese überraschende Beobachtung zeigt daher, dass Baumweite ein wichtiger Parameter sein könnte, der wohl in modernen Designs von Solvern berücksichtigt werden sollte.

This paper analyses how competition over rebates for customer loyalty across product lines affects firms` pricing and consumers generally. If buyers incur firm specific costs or have shop specific tastes then competitive loyalty discounts lower consumer surplus overall and raise profits - the same is true of competitive volume discounts. Competition without these discounts causes all prices to be kept low as larger customers are targetted; with discounts the prices for heavy users drop, but more is extracted from small users. The consumer surplus result is reversed if the differentiation between components as opposed to firms is key. Price discrimination is shown not to be the driving force behind the equilibrium prices - sellers price to steal customers from their rivals. The implications for diverse industries from professional services to cars and supermarkets are explored.

It is well known among practitioners that the seasonal adjustment applied to economic time series involves several decisions to be made by the econometrician. As such, it would always be desirable to have an informed opinion on the risks taken by each of those decisions. In this paper, I assess which disaggregation strategy delivers the best results for the case of the Chilean 1986–2009 GDP quarterly dataset (base year: 2003). This is done by performing an aggregate-by-disaggregate analysis under different schemes, as the fixed base year dataset allows this fair comparison. The analysis is based on seasonal adjustment diagnostics contained in the X-12-ARIMA program plus some statistical tests for robustness. This exercise is relevant for conjunctural economic assessment, as it concerns signal extraction from seasonal, noisy series, direction of change detection, and econometric applications based on reliable and accurate unobserved variables. The results show that it is preferable, in terms of stability, to use the first block of supply-side disaggregation, while demand-side disaggregation tends to be less reliable. This result carries important implications for policymakers aiming to evaluate its short-term effectiveness in both households and firms.

spatial heterogeneity, pollution flow, Solow model We seek to explain the emergence of spatial heterogeneity regarding development and pollution on the basis of interactions associated with the movement of capital and polluting activities from one economy to another. We use a simple dynamical model describing capital accumulation along the lines of a fixed-savings-ratio Solow-type model capable of producing endogenous growth and convergence behavior, and pollution accumulation in each country with pollution diffusion between countries or regions. The basic mechanism underlying the movements of capital across space is the quest for locations where the marginal productivity of capital is relatively higher than the productivity at the location of origin. The notion that capital moves to locations of relatively higher productivity but not necessarily from locations of high concentration to locations of low concentration, does not face difficulties associated with the Lucas paradox. We show that, for a wide range of capital and pollution rates of flow, spatial heterogeneity emerges even between two economies with identical fundamental structures. These results can be interpreted as suggesting that the neoclassical convergence hypothesis might not hold under differential rates of flow of capital and polluting activities among countries of the same fundamental structure.

This contribution studies the role of the size of mutual funds in the evaluation of the fund performance with a data envelopment analysis (DEA) approach, with the aim of studying the issue from different angles and with different statistical tools and investigating the presence of a positive or negative size effect in mutual funds market. Firstly, we discuss the role of fund size in the performance evaluation and wonder whether it is appropriate to include size information among the variables of DEA models. Secondly, we analyse the presence of a relationship between the performance scores and the size of mutual funds using different statistical tests and carry out an empirical investigation on a set of European equity mutual funds. Thirdly, we study scale efficiency and investigate whether the European mutual funds analysed exhibit constant, increasing or decreasing returns to scale.

A long-standing open question raised in the seminal paper of Kalai and Lehrer (1993) is whether or not the play of a repeated game, in the rational learning model introduced there, must eventually resemble the play of exact equilibria, and not just the play of approximate equilibria as demonstrated there. This paper shows that play may remain distant – in fact, mutually singular – from the play of any equilibrium of the repeated game. We further show that the same inaccessibility holds in Bayesian games, where the play of a Bayesian equilibrium may continue to remain distant from the play of any equilibrium of the true game.

The Inventory Routing Problem (IRP) involves the distribution of one or more products from a supplier to a set of clients over a discrete planning horizon. Each client has a known demand to be met in each period and can only hold a limited amount of stock. The product is shipped through a distribution network by one or more vehicles of limited capacity. The objective is to find replenishment decisions minimizing the sum of the storage and distribution costs. In this paper, we present IRP reformulations under the Maximum Level replenishment policy, derived from a single-period substructure. We define a generic family of valid inequalities, and then introduce two specific subclasses for which the separation problem of generating violated inequalities can be effectively solved. A basic Branch-and-Cut algorithm has been implemented to demonstrate the strength of the single-period reformulations. We present computational results for the benchmark instances with 50 clients and 3 periods and 30 clients and 6 periods. The online appendix is available at https://doi.org/10.1287/trsc.2016.0729 .

This article reports on the potential macroeconomic benefits of peace stemming from a reduction in farmer-pastoralist violence in four Middle Belt states of Nigeria (Benue, Kaduna, Nasarawa, and Plateau). Farmers and pastoralists routinely clash over access to farmland, grazing areas, stock routes, and water points for both animals and households. Farmer-pastoralist violence in these states is a relatively low-intensity form of conflict, but it is regionally widespread and chronic, and its incidence is arguably increasing. Using estimates of potential income benefits of peace at the household-level derived from a related study, we herein derive macroeconomic benefits via an input-output model of the Nigerian economy. We estimate these benefits to amount to around 2.8 percent of the nominal Nigerian GDP (or around 0.8 percent of the total Nigerian GDP, inclusive of the informal sector), representing a major macroeconomic opportunity. We break out these benefits by sector, showing that the sectors that stand to gain most from peace are the crop production, food and beverage, livestock, and chemical and petroleum industries. [JEL codes: C65, D74, E01]

In a remarkably short time, economic globalisation has changed the world’s economic order, bringing new challenges and opportunities to SMEs. These processes pushed the need to measure innovation capability, which has become a crucial issue for today’s economic and political decision makers. Companies cannot compete in this new environment unless they become more innovative and respond more effectively to consumers’ needs and preferences – as mentioned in the EU’s innovation strategy. Decision makers cannot make accurate and efficient decisions without knowing the capability for innovation of companies in a sector or a region. This need is forcing economists to develop an integrated, unified and complete method of measuring, approximating and even forecasting the innovation performance not only on a macro but also a micro level. In this recent article a critical analysis of the literature on innovation potential approximation and prediction is given, showing their weaknesses and a possible alternative that eliminates the limitations and disadvantages of classical measuring and predictive methods. / En un plazo increíblemente corto, la globalización económica ha cambiado el orden de la economía, creando nuevos retos y oportunidades a las pequeñas y medianas empresas. Por ello se esta dando la necesidad de crear maneras de medir capacidad de innovación que resulta fundamental para quien debe tomar decisiones politico-economicas. Las compañías no pueden competir en este nuevo entorno a no ser que sean mas innovadoras y respondan de manera más eficiente a las necesidades y preferencias del consumidor-como de hecho se ha mencionado en la Estrategia de Innovación de la UE. Las decisiones no pueden ser tomadas de manera eficiente y adecuada sin el conocimiento de la capacidad de innovación de compañías de un determinada región y/o sector. Esta necesidad está forzando a los economistas a desarrollar un método completo integrado y unificador de medir, aproximar e incluso predecir el rendimiento innovativo tanto a micro como a macro niveles. En este reciente articulo se ha hecho un análisis critico de la literatura que trata sobre aproximaciones y/o predicciones del potencial innovador, mostrando sus defectos y posibles alternativas que eliminarían las limitaciones y desventajas de las mediciones clásicas y métodos predictivos.

Within the developed nations deterioration in the basis of society, as dramatically demonstrated by the Lehman collapse, has reached extreme levels, and currently the formation of pro-change agents is approaching a decisive stage. Here, we will construct a complex systems 'criticality' model, apply it to social change, and examine its reliability and validity. The model derived a power law distribution of the output of social change. The validity of the model was verified by examining vote shares of parties in Japan. Based on the results of this examination, we propose a new quantitative strategy "information entropy enhancement" for social change.

In order to evaluate the performance of socially responsible investment (SRI) funds, we propose some models which use data envelopment analysis and can be computed in all phases of the business cycle. These models focus on the most crucial elements of an investment in mutual funds. In the literature both constant and variable returns to scale DEA models have been used to evaluate the performance of mutual funds. An empirical investigation carried out on European SRI equity funds indicates that for the funds analyzed the returns to scale are constant. Another aspect taken into account by the empirical investigation is the measurement of the degree of social responsibility of SRI equity funds in the various European countries. In addition, we have analyzed the performance of the funds considered with the different DEA models proposed, which differ in the way the ethical objective is taken into account. Moreover, the paper focuses on another crucial issue regarding socially responsible investing: the comparison of the performances between SRI and non SRI funds; the empirical study suggests that the ethical objective can be pursued without having to renounce financial rewards.

A certain spectrum, indexed by a\in[0,\infty], of upper bounds P_a(X;x) on the tail probability P(X\geq x), with P_0(X;x)=P(X\geq x) and P_\infty(X;x) being the best possible exponential upper bound on P(X\geq x), is shown to be stable and monotonic in a, x, and X, where x is a real number and X is a random variable. The bounds P_a(X;x) are optimal values in certain minimization problems. The corresponding spectrum, also indexed by a\in[0,\infty], of upper bounds Q_a(X;p) on the (1-p)-quantile of X is stable and monotonic in a, p, and X, with Q_0(X;p) equal the largest (1-p)-quantile of X. In certain sense, the quantile bounds Q_a(X;p) are usually close enough to the true quantiles Q_0(X;p). Moreover, Q_a(X;p) is subadditive in X if a\geq 1, as well as positive-homogeneous and translation-invariant, and thus is a so-called coherent measure of risk. A number of other useful properties of the bounds P_a(X;x) and Q_a(X;p) are established. In particular, quite similarly to the bounds P_a(X;x) on the tail probabilities, the quantile bounds Q_a(X;p) are the optimal values in certain minimization problems. This allows for a comparatively easy incorporation of the bounds P_a(X;x) and Q_a(X;p) into more specialized optimization problems. It is shown that the minimization problems for which P_a(X;x) and Q_a(X;p) are the optimal values are in a certain sense dual to each other; in the case a=\infty this corresponds to the bilinear Legendre--Fenchel duality. In finance, the (1-p)-quantile Q_0(X;p) is known as the value-at-risk (VaR), whereas the value of Q_1(X;p) is known as the conditional value-at-risk (CVaR) and also as the expected shortfall (ES), average value-at-risk (AVaR), and expected tail loss (ETL). It is shown that the quantile bounds Q_a(X;p) can be used as measures of economic inequality. The spectrum parameter, a, may be considered an index of sensitivity to risk/inequality.

Se establece un modelo que describe la movilidad interna y externa a nivel provincial de la población ecuatoriana, considerando su autoidentificación étnica (indígena y no indígena). El estudio utiliza las cadenas de Markov; para desarrollar el modelo estocástico, se han tomado como base los datos del Censo de Población y Vivienda 2010, elaborado por el Instituto Nacional de Estadística y Censos (INEC).

ACL-2; International audience; The Ramsey model of economic growth is revisited from the perspective of viability theory. The Ramsey model, augmented with minimal consumption and sustainability criteria, becomes a viability problem. The framework allows for a clear picture of optimal viable, optimal nonviable, and viable nonoptimal paths. The drastic sacrifices in terms of present consumption required by the implementation of Brundtland sustainability are visualized, the rich countries bearing the major part of the burden. The econometric analysis of viability sets enhances the role of technological progress in ensuring Brundtland sustainability. Preference parameters such as the pure time preference rate are statistically nonsignificant.

A main problem for macroeconomic studies continues to be the estimation of capital stock and some derived indicators like coefficient of capital, depreciation rate, etc. In this way we are proposing a simple and intuitively model in order to estimate such basic macroeconomic indicators but avoiding to knowing the amount of capital stock. By applying a simulation model in case of European Union data for a set of periods, we obtained some relevant result. One of them is referring to the negative impact of last global crisis on the coherence of a classic type model. Such model is adequate mostly for a period of continuous increasing in GDP as it was for EU during the period 2000-2007.

This paper explores long wave theory, including Kondratieff's theory of cycles in production and relative prices; Kuznets's theory of cycles arising from infrastructure investments; Schumpeter's theory of cycles due to waves of technological innovation; Goodwin's theory of cyclical growth based on employment and wage share dynamics; Keynes–Kaldor–Kalecki's demand and investment-oriented theories of cycles; and Minsky's financial instability hypothesis whereby capitalist economies show a genetic propensity to boom–bust cycles. This literature has been out of favor for many years but recent developments suggest a re-examination is warranted and timely.

This paper develops two methodological approaches for calculating the float factor of the stock market index (IPC) of the Mexican stock market (BMV). The first one assumes that the free float factor is approximated by the normalization of the daily market rotation of each title, while the second one uses the relative daily market rotation. In both cases, the float factor is simulated by a variable with mean reversion similar to the one proposed in Cox, Ingersoll and Ross’ model (1985). The methodologies we have established here remedy the inability to replicate the IPC because of the elements of confidentiality that the float factor currently has. Moreover, the proposed flotation factor can be updated instantly given the nature of the developed models. The paper shows that the weights of the firms in the IPC, calculated by using the formulated methodologies, are substantially different from those provided by the BMV when applying its flotation factor, which contains discretionary components of information difficult to verify.

This paper is an application of delay differential equations to entrepreneurship and unemployment. It shows that the results of empirical studies can be replicated through a simple DDE. The paper also carries out a comparative study between a solution of a DDE and the observation of cyclic behaviors. The calculated delay (and growth rate) of the entrepreneurship DDE for the US and Spain is 1.25 years (1.25), for Ireland is 1.75 years (0.89), and for the UK is 2 years (0.78). The delay (and growth rate) of the unemployment DDE for the US and Ireland is 1.5 years (1.04), for Spain is 2 years (0.78), and for the UK is 2.5 years (0.62).

We provide an analytical approach that facilitates understanding the bifurcation mechanism of a wide class of economic models involving spatial agglomeration of economic activities. The proposed method overcomes the limitations of the Turing (1952) approach that has been used to analyze the emergence of agglomeration in the multi-regional core-periphery (CP) model of Krugman (1993, 1996). In other words, the proposed method allows us to examine whether agglomeration of mobile factors emerges from a uniform distribution and to analytically trace the evolution of spatial agglomeration patterns (i.e., bifurcations from various polycentric patterns as well as a uniform pattern) that these models exhibit when the values of some structural parameters change steadily. Applying the proposed method to the multi-regional CP model, we uncover a number of previously unknown properties of the CP model, and notably, the occurrence of “spatial period doubling bifurcation” in the CP model is proved.

The purpose of the paper is to contribute to the use of evaluator and utility functions in order to increase the reliability of scorecard based intellectual capital (IC) measurement methods and to express and aggregate the utility of IC components to an organization. The conducted field experiment integrates the results of interviews with 23 brand name customers by examining the customer satisfaction measuring practice of service provider companies. Our main finding is that adequately calibrated evaluator functions assign perceived customer satisfaction to its scorecard based measured values and reduce the distortions of scorecard based measurements. The originality of the research lies in expressing and aggregating the utilities of IC components to the organization by interpreting the evaluator function as a kind of utility function. This application allows the joint use of financial valuation and scorecard based measurement in the same performance management system.

Lately, Internet constitutes a major tool for transactions in every aspect and supports innovative marketing policies. Broadband Internet has become “the key to success” for businesses, as it offers various advantages and benefits through Internet marketing (e-marketing) policies. In Greece, mountainous areas are usually covered with snow during winter months; so, skiing centers have become an important asset for winter tourism. The Internet evolution and the development of network infrastructure enhance marketing policies for winter tourism activities. This paper studies the use of marketing policies in Greek skiing centers through the Internet, such as promotional activities, website interactivity, accommodation & entertainment information, online weather forecast, guest book, etc Therefore, the paper aims to optimize and evaluate skiing centers in Greece, qualitatively and quantitatively according to e-marketing policies used as criteria, based on the multicriteria method of PROMETHEE II and further to classify them in groups. Finally we identify and describe the optimum group of skiing centers to be used as a model with enhanced customer communication services.

A theoretical model is developed for the ratio primary-surplus/GDP that a Country has to attain over a given number of years, to lower its public debt from the present value to one a-priori fixed. Such a ratio depends on the average interest rate paid on the outstanding stock of debt as well as inflation and real growth rates. The ratio primary-surplus/GDP is then determined for Germany, Greece and Italy, supposing that 20 years are necessary for lowering the debt to 60% of GDP, as indicated in the Budget Pact approved by 25 EU member States. Results are reported in graphs and show how the German debt can be easily diminished, whilst debts in Greece and Italy can be reduced with a greater difficulty.

La presente investigación analiza el gasto de las familias ecuatorianas, considerando los siguientes rubros: alimentación, salud, transporte, diversión, educación, artículos de recreo, joyería, vehículos para uso del hogar junto con su mantenimiento, vestido y calzado, comunicaciones, servicios del hogar, servicio doméstico, electrodomésticos, impuestos, servicios profesionales, periódicos, revistas, cigarrillos, cervezas y bebidas alcohólicas. Además, se toma en cuenta la composición y tamaño de las familias. Esto último permite establecer escalas de equivalencia en función de los diversos tipos de familias, pues se hace evidente las diferencias en el gasto relativo que incurren los hogares con una distinta composición. Finalmente, a través de las diferencias establecidas en el gasto relativo, se puede calcular el costo que involucra tener un miembro más; en particular, el costo de tener un hijo. Para lograr los objetivos planteados, se estima la curva de Engel a través de distintas formas funcionales, no lineales, como las formas flexibles de Fourier. En este estudio se utilizan los datos de la Encuesta de Condiciones de Vida (ECV) efectuada por el INEC durante el período 2005-2006, porque es la fuente de información más reciente que contiene todos los datos necesarios para el estudio. INEC

Budgets are important instruments for organisational management, control and planning. Following the urgency of contemporary business challenges and radical shift in business structure owing to global financial volatility, there is a growing need to rethink budgeting. Also, factors such as increasing shareholders’ expectations, impact of new technology, knowledge economy, innovation and other organisational integers have impacted on how managers think of firms in relation to budgeting. Given the limitations posed by traditional budgeting system as well as the urgency of recent global financial meltdown, there is pressure on managers and leaders to devise other ways to effectively manage organisations for productivity and competitiveness. In this paper, the Balanced Scorecard model will be used as an alternative method to traditional budgeting system. Consequently, the major concern of this paper is to articulate the limitations of (traditional) budgeting in relation to the Balanced Scorecard (BSC) method as well as in the context of what Hope and Fraser (2003) called ‘‘Beyond Budgeting’’ schema for more effective ways of managing organisations in the 21st century. The dilemma of ‘‘annual performance trap’’ is also implicated in this light. As budget restricts innovative, fluid and value-generating ways of managing organisations through its instrumentality of control and mechanistic co-ordination, troubled or distressed organisations are struggling to leverage on their opportunities. This adversely affects productivity levels.

Neben hochwertigen Publikationen nehmen Rankings einen immer größeren Stellenwert in der Wissenschaft ein. Der vorliegende Artikel stellt ein neues Verfahren zur Klassifizierung von Wissenschaftlern vor, die Archetypal Analysis, und illustriert dies anhand von Daten aus dem RePEc-Netzwerk, eines der umfangreichsten Datenbanken von wissenschaftlichem Output in den Wirtschaftswissenschaften. Die Archetypal Analysis ist ein neuer Klassifikationsansatz, der die Identifikation von extremen Beobachtungen in einem hochdimensionalen Datensatz ermöglicht. Diese Extremwerte werden als Archetypen bezeichnet. Darauf aufbauend können alle im Datensatz erfassten Wissenschaftler anteilig diesen Archetypen zugeordnet werden. Der Ansatz erlaubt eine differenziertere Darstellung von Charakterisierungen, die auch über die Anzahl der verwendeten Variablen hinausgehen kann.

In the first part of the study we introduce fuzzy sets that correspond to comparative indicators for measuring sustainable development of tourism. In the second part of the study it is shown, on the base of model created, how one can determine the value of sustainable tourism development in protected areas based on the following established groups of indicators: to assess the economic status, to assess the impact of tourism on the social component, to assess the impact of tourism on cultural identity, to assess the environmental conditions and indicators as well as to assess tourist satisfaction, all using fuzzy logic. It is also shown how to test the confidence in the rules by which, according to experts, appropriate decisions can be created in order to protect biodiversity of protected areas.

In this paper, a new valuation methodology is tested as an alternative way to value European options by applying Fast Fourier Transform (FFT) on Lévy processes. It is shown how this new approach can be applied to the Variance-Gamma model by Madan, Carr and Chang (1998). This model has a closed form formula, which can be obtained, as in many other models, by partial differential equations or by probabilistic methods, but even these methodologies will not prove to be useful when we encounter ourselves with more complex models. Nevertheless, if we take into account the fact that there is a one-to-one relationship between a characteristic function of an exponential Lévy process and its probability density and that this cash flows are known in closed forms or can be expressed in terms of special mathematic functions, then it is possible to use this new methodology to obtain an alternate and maybe simpler valuation forms for models which do not have a closed form solution. Madan, Carr and Changs model is a particular case of general exponential Lévy processes. If there is a way to develop a new valuation method by using Fourier transform and this method proves to give same results as closed form solutions or by numerical method solutions, then we could be on our way to find simpler ways to price assets than using a traditional approach

The growth or decline of a region depends on its power to pull and retain both business and the right blend of people to run them. This pulling power depends on what we call the "Image" of the region, a variable which expresses the region's present state of development and future prospects and may be defined as a function of a multitude of factors; economic, social and environmental ones. The Image of a region may prove a very useful tool for planning purposes, since it doesn't only give an early diagnosis of any possible changes, sometimes discontinuous, in the region's pattern of development, but it also indicates the reasons for those changes. Hence, it may be used as the basis for designing appropriate measures to assist a region's development. The objective of this paper is to define a region's image, based on an analysis of the business and the residential location process, to identify, through literature, the factors needed to quantify this image and finally, to suggest ways of measuring these factors.

This paper proposes the construction of the Minimum Food Security Quota (MFSQuota)using mathematical economic modelling in real time. The MFS-Quota fixes a certain amount of annual food storage to prepare a country for any natural or social disasters. Any country can construct its own MFS-Quota for “food security policy”.

In recent years, the studies related to the healthcare market, place emphasis on the importance of healthcare competition in terms of high quality services and decreases in the amount of healthcare expenses. To this end, many economists and policy makers recommend different strategies related to competition among hospitals and health systems in the healthcare market. In this paper, to measure the competition level of healthcare market, we use such factors as; determination of competitors and services delivered by hospitals, determination of market scope and the measurement method of basic competition, demonstrating the role of insurance companies. In this respect, HHI index exhibiting the concentration in local level is used in order to measure competition level among hospitals. Consequently, it is concluded that an oligopoly structure exists in hospital market.

We consider two models of lump sum taxation in pure exchange economy in which the state imposes taxes on (or offers financial aid to) economic agents characterized by their demand functions and initial resources. In the first model the state has its own preferences and uses the collected money to enter the market and maximize its utility while in the second model it uses the taxes to acquire fixed resources necessary for its functioning. We study the existence and structure of equilibria in general economies, the possibility of using taxation to realize Pareto optimal allocations, and the role of taxation as a possible cause of inflation. Special attention is paid to economies with gross substitutability. Bibliography 18 items.

The paper estimates the matrix of expectations of the economic factors that defined the local and foreign trade in the Mexican industry. With an application of the Black-Scholes-Merton model, it warns about the financial problems that may face an exporting company

El principal resultado de este artículo consiste en la resolución del problema inverso del modelo de Black-Cox (1976), usando el método propuesto por Sukhomlin (2007). Se parte del enfoque retrógrado (backward) para obtener una expresión exacta de la volatilidad implícita en función de parámetros cuantificables con datos de mercado y de variables conocidas. Se descubre la existencia de dos valores de la volatilidad para un activo subyacente en elmodelo referido, lo que indica que las asunciones tradicionales no lo definen de manera unívoca. Se encuentra la causa de que el modelo de Black-Cox contenga dos valores de la volatilidad. Además, se lleva a cabo una simulación, afin de verificar, numéricamente, que la expresión obtenida para la volatilidad es la inversión de la fórmula que representa la probabilidad de que la firma no alcance un nivel de insolvencia antes del tiempo de madurez de la deuda. Finalmente, se resuelve el problema de calibración de mercadodesde el punto de vista directo (forward), encontrándose una expresión que resulta de mayor utilidad para los agentes de mercado. || The main result of this paper consists in the resolution of the inverse problem for the Black-Cox (1976) model, using the method proposed by Sukhomlin (2007). Based on the backward approach, we obtain an exact expression of the implied volatility expressed as a function of quantifiable market parameters and known variables. We discover the existence of two values of the volatility for an underlying asset, in the referred model, which means that the model's traditional assumptions do not define it univocally. We findthe cause that the Black-Cox model contains two values of the volatility. Besides, we carry out a simulation in order to verify, numerically, that our volatility expression is in fact the inversion of the formula that represents the probability that the firm has not reached the reorganization boundary before the debt expires. Finally, we solve the market calibration problem from the forward approach, finding an expression that is more useful for market agents.

El índice de marginación elaborado por el Consejo Nacional de Población es una medida ordinal que indica el grado de exclusión que experimentan las regiones del país (estados, municipios y localidades) del disfrute del desarrollo económico. Este indicador es ampliamente utilizado, entre otras cosas, para focalizar programas de combate a la pobreza. Sin embargo, debido a la metodología empleada en su construcción, no es posible emplearlo para medir la efectividad de algunos programas gubernamentales orientados a disminuir el rezago social. Aquí se propone una metodología para la cardinalización del índice a fin de que éste pueda emplearse como una medida cardinal que posibilite cuantificar las mejoras o retrocesos en el nivel de bienestar de las diferentes zonas del país. Adicionalmente se presenta una aplicación de la técnica para evaluar el efecto de las transferencias del Ramo 33 en los cambios de la marginación a nivel estatal.

Article considers the structure of expert system for effective management of normal daily regimes of Georgian power system. In contrast to existing structure, this structure includes the block of solution of conflicts among production rules. This block with blocks of logical output and calculation forms one big block. Advantage of such method is that solution of conflicts among rules takes place in the process of logical output. Therefore, process of making effective decisions is faster.

This paper may be understood as a continuation of Topsoe's seminal paper [F. Topsoe, Compactness in spaces of measures, Studia Math. 36 (1970) 195–212] to characterize, within an abstract setting, compact subsets of finite inner regular measures w.r.t. the weak topology. The new aspect is that neither assumptions on compactness of the inner approximating lattices nor nonsequential continuity properties for the measures will be imposed. As a providing step also a generalization of the classical Portmanteau lemma will be established. The obtained characterizations of compact subsets w.r.t. the weak topology encompass several known ones from literature. The investigations rely basically on the inner extension theory for measures which has been systemized recently by Konig [H. Konig, Measure and Integration, Springer, Berlin, 1997; H. Konig, On the inner Daniell-Stone and Riesz representation theorems, Doc. Mat. 5 (2000) 301–315; H. Konig, Measure and integration: An attempt at unified systematization, Rend. Istit. Mat. Univ. Trieste 34 (2002) 155–214].

In this paper the initial analysis of NDT laboratory is presented by means of agent-based modelling. For the purpose of analysis, laboratory is taken into account as a complex system consisting of three agents ; equipment, personnel and specimens. Interaction between the agents is circular. In that sense, the agents are mutually interconnected in a way that one agent simultaneously interacts with others. According to the interactions specific for NDT laboratories, the response of total testing time is presented considering various number of laboratory personnel while each operator has different skills and ability. Agent personnel has to perform testing of specimens. Since the complexity of specimens is quite diverse the specimens are represented as an agent. Additionally, during the whole time sequence of testing a certain specimen, operator is using NDT equipment relevant for the testing method, while the particular time of usage of the equipment can be shorter than the whole testing time. Availability of the equipment is therefore another agent. The evaluated outcome is the total testing time. Presented results are obtained carrying out a simulation by means of multi-agent modelling and simulation tool named “ ENTORAMA” . Finally, the overall laboratory's performance is given in the respect of the number and structure of the laboratory personnel.

In this paper we have found an analytical formula for a copula that connects the numbers Ni of customers in the nodes of a Gordon and Newell queueing network. We have considered two cases: the first one is the case of the network with 2 nodes, and the second one is the case of the network with at least 3 nodes. The analytical formula for the second case has been found for the most general case (none of the constants from a list is equal to a given value), and the other particular cases have been obtained by limit.

The paper analyses how the data envelopment analysis (DEA) and fuzzy set theory can be used to measure and evaluate the efficiency of a hierarchical system with n decision making units and a coordinating unit. It is presented a model for determining the of activity levels of decision making units so as to achieve both fuzzy objectives of achieving global target levels of coordination unit on the inputs and outputs and individual target levels of decision making units, and then some methods to resolve fuzzy models are proposed.

The Credit Default Swap (CDS) is the most popular credit derivative and it is used as insurance against the risk of default by a particular company, known as a reference entity. If a portfolio of debt instruments is created with a complex structure where the cash flows from such portfolio are channeled to different categories of investors, we have a collateralized debt obligation (CDO). If the CDO is formed by a portfolio of CDS it is called a Synthetic CDO. The synthetic CDO transfers to market the credit risk of the portfolio. In this paper I describe the synthetic CDO valuation process and I propose an algorithm for the fair pricing of tranches, which does not require Monte Carlo simulation or Copulas, even with different notional principal values

Harbaugh's daughter went to a French school at which every day before class, everyone in the class must kiss each other. It is easy to see that a class of 35 kids must engage in 595 kisses. Organizing the kissing for the purpose of time-saving and predicting how much time it would take are proposed in this pedagogical note inspired by the entertaining puzzle made by Harbaugh. We also illustrate how this problem-solving case study, requiring no mathematics but careful reasoning, might be incorporated in teaching undergraduate students majoring in economics or business.

Se propone y se desarrolla un procedimiento desde el paradigma de la complejidad que, partiendo de las características más generales que permiten identificar a las organizaciones turísticas como sistemas sociales humanos complejos, valora los impactos de la capacitación en la consecución de las metas organizacionales. El procedimiento se aborda desde la aplicación del modelo de valoración de los efectos olvidados en las relaciones de causalidad del sistema de acciones de capacitación, identificando a través de la matriz de relación incidencia-dependencia, la cohesión estructural de la estrategia de capacitación y los lazos de interacción entre las diferentes acciones expresadas en grafos. Finalmente, en las conclusiones, se destacan los valores del modelo propuesto y aplicado, como contribución al perfeccionamiento de las estrategias de capacitación. = A procedure is developed from the paradigm of the complexity, starting from their most general characteristics to identify tourism organizations as social human complex systems. This procedure values the impacts of the training in the achievement of the organizational goals. The model of forgotten effects to the causality relationships of the system of training actions and, by using the relationship matrix of incidence-dependence, the structural cohesion is identified in the training strategy. The interaction links among the different actions have been expressed by graphs. Finally, the conclusions bring out the values of the proposed and applied method as a contribution to the improvement of the training strategies.

In this paper we apply random matrix theory (RMT) to the analysis of cross-correlation matrix C constructed from daily returns of 65 stocks traded at the Bolsa Mexicana de Valores during a trading period of eighth years. We find that the statistics of most of the eigenvalues in the spectrum of C agrees with the prediction of RMT, but there are deviations for a few of the larger eigenvalues. We show that C has the universal properties of the Gaussian orthogonal ensemble of random matrices. Furthermore, we analyze the eigenvectors of C through their inverse participation ratio, such analysis allow us to indicate matrix C has a random band structure

En este artículo, los autores pretenden mostrar y explicar cómo la Teoría de Lie se puede aplicar a la resolución de algunos problemas relativos a la Economía y a las Finanzas. Concretamente, se realiza un análisis de dos de esos problemas y se discuten tanto sus aspectos matemáticos como el acercamiento hecho desde la Teoría de Lie para su resolución. Igualmente, se indican los avances más recientes existentes en esta línea de investigación, mencionando también algunos problemas abiertos que pueden ser tratados en futuros trabajos. = This paper shows and explains two problems in Economics and Finance, both dealt with a Lie Theory approach. So, mathematical aspects for these approaches are put forward and discussed in several economic problems which have been previously considered in the literature. Besides, some advances on this topic are also shown, mentioning some open problems for future research.

During the last few years, the Second Banking Directive has set out the principles of banking in the single European financial market and provided equal competitive conditions for all European banking institutions. Thus, banks have been forced to be more competitive and to implement bank rating systems to evaluate their financial risks. The present study evaluates the performance and efficiency of the commercial and cooperative banks in Greece for the period 2003-2004. Moreover, the Greek banks are rated based on their performance. The ranking result can be used to analyse the strengths and weaknesses of a bank compared to its competitors and it can serve as a basis for the construction of a rating system for Greek banks. The results obtained indicate that commercial banks are tending to increase their accounts, to attract more customers and ameliorate their financial indices, thereby becoming more competitive and maximizing their profits. Concerning the cooperative banks in Greece, the conclusions are not so uniform, since there are banks that are enjoying considerably increased profits and market shares, and others whose financial indices seem to be deteriorating.

A microeconomic, agent based framework to dynamic economics is formulated in a materialist approach. An axiomatic foundation of a non-equilibrium microeconomics is outlined. Economic activity is modelled as transformation and transport of commodities (materials) owned by the agents. Rate of transformations (production intensity), and the rate of transport (trade) are defined by the agents. Economic decision rules are derived from the observed economic behaviour. The non-linear equations are solved numerically for a model economy. Numerical solutions for simple model economies suggest that the some of the results of general equilibrium economics are consequences only of the equilibrium hypothesis. We show that perfect competition of selfish agents does not guarantee the stability of economic equilibrium, but cooperativity is needed, too.

Path dependency is defined, and three different specific concepts of path dependency – cumulative causation, lock in, and hysteresis – are analyzed. The relationships between path dependency and equilibrium, and path dependency and fundamental uncertainty are also discussed. Finally, a typology of dynamical systems is developed to clarify these relationships.

Summary: In a Hayek-Friedman-Lucas world, market economies are assumed to be natural, stable, and ergodic; hence, government policies are harmful to their efficiency. We develop a nonlinear dissipative dynamic model that shows that market economies instead live on the edge of chaos. We next appeal to the theory of differential equation to show that if they do not usually dissipate the totality of the information produced by their evolution it is due to a far-off self-organized equilibrium brought about by a spontaneous phase change originating in an optimal government policy.

This paper incorporates text data from MLS listings from Atlanta, GA into a hedonic pricing model. Text is found to decrease pricing error by more than 25%. Information from text is incorporated into a linear model using a tokenization approach. By doing so, the implicit prices for various words and phrases are estimated. The estimation focuses on simultaneous variable selection and estimation for linear models in the presence of a large number of variables. The LASSO procedure and variants are shown to outperform least-squares in out-of-sample testing.