A stopping rule while searching for optimal solution of facility-location

Solutions to combinatorial optimization, such as p-median problems of locating facilities, frequently rely on heuristics to minimize the objective function. The minimum is sought iteratively and a criterion is needed to decide when the procedure (almost) attains it. However, pre-setting the number of iterations dominates in OR applications, which implies that the quality of the solution cannot be ascertained. A small branch of the literature suggests using statistical principles to estimate the minimum and use the estimate for either stopping or evaluating the quality of the solution. In this paper we use test-problems taken from Baesley's OR-library and apply Simulated Annealing on these p-median problems. We do this for the purpose of comparing suggested methods of minimum estimation and, eventually, provide a recommendation for practioners. An illustration ends the paper being a problem of locating some 70 distribution centers of the Swedish Post in a region.

A fuzzy rule-based decision support system for Duodopa treatment in Parkinson

A decision support system (DSS) was implemented based on a fuzzy logic inference system (FIS) to provide assistance in dose alteration of Duodopa infusion in patients with advanced Parkinson’s disease, using data from motor state assessments and dosage. Three-tier architecture with an object oriented approach was used. The DSS has a web enabled graphical user interface that presents alerts indicating non optimal dosage and states, new recommendations, namely typical advice with typical dose and statistical measurements. One data set was used for design and tuning of the FIS and another data set was used for evaluating performance compared with actual given dose. Overall goodness-of-fit for the new patients (design data) was 0.65 and for the ongoing patients (evaluation data) 0.98. User evaluation is now ongoing. The system could work as an assistant to clinical staff for Duodopa treatment in advanced Parkinson’s disease.

Rule versus interaction function : evaluating regional aggregations of commuting flows in Sweden

The aim of this paper is to evaluate the performance of two divergent methods for delineating commuting regions, also called labour market areas, in a situation that the base spatial units differ largely in size as a result of an irregular population distribution. Commuting patterns in Sweden have been analyzed with geographical information system technology by delineating commuting regions using two regionalization methods. One, a rule-based method, uses one-way commuting flows to delineate local labour market areas in a top-down procedure based on the selection of predefined employment centres. The other method, the interaction-based Intramax analysis, uses two-way flows in a bottom-up procedure based on numerical taxonomy principles. A comparison of these methods will expose a number of strengths and weaknesses. For both methods, the same data source has been used. The performance of both methods has been evaluated for the country as a whole using resident employed population, self-containment levels and job ratios for criteria. A more detailed evaluation has been done in the Goteborg metropolitan area by comparing regional patterns with the commuting fields of a number of urban centres in this area. It is concluded that both methods could benefit from the inclusion of additional control measures to identify improper allocations of municipalities.

Towards Presidential Rule in Ukraine : Hybrid Regime Dynamics under Semi-Presidentialism

This article sets out to analyse recent regime developments in Ukraine in relation to semi-presidentialism. The article asks: to what extent and in what ways theoretical arguments against semi-presidentialism (premier-presidential and president-parliamentary systems) are relevant for understanding the changing directions of the Ukrainian regime since the 1990s? The article also reviews the by now overwhelming evidence suggesting that President Yanukovych is turning Ukraine into a more authoritarian hybrid regime and raises the question to what extent the president-parliamentary system might serve this end. The article argues that both kinds of semi-presidentialism have, in different ways, exacerbated rather than mitigated institutional conflict and political stalemate. The return to the president-parliamentary system in 2010 – the constitutional arrangement with the most dismal record of democratisation – was a step in the wrong direction. The premier-presidential regime was by no means ideal, but it had at least two advantages. It weakened the presidential dominance and it explicitly anchored the survival of the government in parliament. The return to the 1996 constitution ties in well with the notion that President Viktor Yanukovych has embarked on an outright authoritarian path.

Leakage Detection And Localization Method Based On A Hybrid Inverse/Direct Modelling Approach Suitable For Handling Multiple-Leak Scenarios

When an accurate hydraulic network model is available, direct modeling techniques are very straightforward and reliable for on-line leakage detection and localization applied to large class of water distribution networks. In general, this type of techniques based on analytical models can be seen as an application of the well-known fault detection and isolation theory for complex industrial systems. Nonetheless, the assumption of single leak scenarios is usually made considering a certain leak size pattern which may not hold in real applications. Upgrading a leak detection and localization method based on a direct modeling approach to handle multiple-leak scenarios can be, on one hand, quite straightforward but, on the other hand, highly computational demanding for large class of water distribution networks given the huge number of potential water loss hotspots. This paper presents a leakage detection and localization method suitable for multiple-leak scenarios and large class of water distribution networks. This method can be seen as an upgrade of the above mentioned method based on a direct modeling approach in which a global search method based on genetic algorithms has been integrated in order to estimate those network water loss hotspots and the size of the leaks. This is an inverse / direct modeling method which tries to take benefit from both approaches: on one hand, the exploration capability of genetic algorithms to estimate network water loss hotspots and the size of the leaks and on the other hand, the straightforwardness and reliability offered by the availability of an accurate hydraulic model to assess those close network areas around the estimated hotspots. The application of the resulting method in a DMA of the Barcelona water distribution network is provided and discussed. The obtained results show that leakage detection and localization under multiple-leak scenarios may be performed efficiently following an easy procedure.

The ex-Ante non-optimality of the Dempster-Schafer updating rule for ambiguous beliefs

The most widely used updating rule for non-additive probalities is the Dempster-Schafer rule. Schmeidles and Gilboa have developed a model of decision making under uncertainty based on non-additive probabilities, and in their paper “Updating Ambiguos Beliefs” they justify the Dempster-Schafer rule based on a maximum likelihood procedure. This note shows in the context of Schmeidler-Gilboa preferences under uncertainty, that the Dempster-Schafer rule is in general not ex-ante optimal. This contrasts with Brown’s result that Bayes’ rule is ex-ante optimal for standard Savage preferences with additive probabilities.

Term structure dynamics and no-arbitrage under the Taylor rule

A determinação da taxa de juros estrutura a termo é um dos temas principais da gestão de ativos financeiros. Considerando a grande importância dos ativos financeiros para a condução das políticas econômicas, é fundamental para compreender a estrutura que é determinado. O principal objetivo deste estudo é estimar a estrutura a termo das taxas de juros brasileiras, juntamente com taxa de juros de curto prazo. A estrutura a termo será modelado com base em um modelo com uma estrutura afim. A estimativa foi feita considerando a inclusão de três fatores latentes e duas variáveis ​​macroeconômicas, através da técnica Bayesiana da Cadeia de Monte Carlo Markov (MCMC).

Bailey's rule for the welfare of inflation: a theoretical foundation

This paper demonstrates that for a very general class of monetary models (the Sidrauski type models and the cash-in-advance models), Bailey’s rule to evaluate the welfare efect of infation is in deed accurate. The result applies for any technology or preference, if the long-run capital stock does not depend on the ination rate. In general, a dynamic version of Bailey’s rule is established. In particular, the result extends to models in which there is a banking sector that supplies money substitutes services. A dditionally, it is argued that the relevant money demand concept for this issue- the impact of in ination under welfare- is the monetary base.

Testing the optimality of aggregate consumption decisions: is there rule-of-thumb behavior?

Consumption is an important macroeconomic aggregate, being about 70% of GNP. Finding sub-optimal behavior in consumption decisions casts a serious doubt on whether optimizing behavior is applicable on an economy-wide scale, which, in turn, challenge whether it is applicable at all. This paper has several contributions to the literature on consumption optimality. First, we provide a new result on the basic rule-of-thumb regression, showing that it is observational equivalent to the one obtained in a well known optimizing real-business-cycle model. Second, for rule-of-thumb tests based on the Asset-Pricing Equation, we show that the omission of the higher-order term in the log-linear approximation yields inconsistent estimates when lagged observables are used as instruments. However, these are exactly the instruments that have been traditionally used in this literature. Third, we show that nonlinear estimation of a system of N Asset-Pricing Equations can be done efficiently even if the number of asset returns (N) is high vis-a-vis the number of time-series observations (T). We argue that efficiency can be restored by aggregating returns into a single measure that fully captures intertemporal substitution. Indeed, we show that there is no reason why return aggregation cannot be performed in the nonlinear setting of the Pricing Equation, since the latter is a linear function of individual returns. This forms the basis of a new test of rule-of-thumb behavior, which can be viewed as testing for the importance of rule-of-thumb consumers when the optimizing agent holds an equally-weighted portfolio or a weighted portfolio of traded assets. Using our setup, we find no signs of either rule-of-thumb behavior for U.S. consumers or of habit-formation in consumption decisions in econometric tests. Indeed, we show that the simple representative agent model with a CRRA utility is able to explain the time series data on consumption and aggregate returns. There, the intertemporal discount factor is significant and ranges from 0.956 to 0.969 while the relative risk-aversion coefficient is precisely estimated ranging from 0.829 to 1.126. There is no evidence of rejection in over-identifying-restriction tests.

Repensando a relação entre estado, direito e desenvolvimento: os limites do paradigma rule of law e a relevância das alternativas institucionais

Assumindo a primazia da abordagem institucionalista na agenda contemporânea do desenvolvimento, este artigo procurará discutir alguns de seus limites, descritivos e normativos, no que tange, em especial, ao sistema financeiro. Particularmente, procurar-se-á sugerir que os programas de difusão do rule of law têm se constituído em um paradigma estreito do papel exercido pelo direito, segundo a qual cabe ao ambiente jurídico cumprir, apenas e tão somente, a função de garantidor dos interesses de investidores privados, entendidos como atores centrais de um modelo de financiamento baseado em transações de mercado. O texto sugere que o paradigma rule of law, como estratégia de promoção do desenvolvimento, tem dificuldade em lidar com a existência de alternativas institucionais de organização econômica e financeira, para além de um modelo de mercado baseado em atores atomizados e carentes de segurança jurídica. Um exemplo disso, que escapa do instrumental tradicional, é o modelo brasileiro de financiamento, que, apesar de ter vivenciado inúmeras reformas institucionais, dedicadas a elevar o nível de proteção de investidores, ainda concentra em um banco de desenvolvimento – o BNDES – grande parte do financiamento de longo prazo do país. O artigo assume, portanto, que, sim, o direito e as instituições, de fato, importam para o desenvolvimento, mas há uma variedade de possibilidades e funções a serem exercidas pelos arranjos institucionais e ferramentas jurídicas – muito além do que supõem os programas de rule of law. Uma bem sucedida organização institucional baseada em um banco de desenvolvimento é um exemplo disso.