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See detailL'expérience de la valeur: Ehrenfels et Meinong
Dewalque, Arnaud ULg

E-print/Working paper (2015)

A supposer que le concept de valeur soit un concept empirique, qui a sa source dans l'expérience, de quel type est l'expérience de la valeur? Dans les pages suivantes, je suggère qu’Ehrenfels et Meinong ... [more ▼]

A supposer que le concept de valeur soit un concept empirique, qui a sa source dans l'expérience, de quel type est l'expérience de la valeur? Dans les pages suivantes, je suggère qu’Ehrenfels et Meinong ont apporté certaines améliorations substantielles à la position de Brentano. Ces améliorations résident essentiellement dans les deux points suivants : (1) les volitions se caractérisent par une dimension « active » ou conative qui fait défaut aux sentiments, ce qui interdit de les ranger dans une seule et même « classe » de phénomènes psychiques ; (2) le concept de valeur trouve son origine empirique dans les volitions ou les phénomènes conatifs, non dans les sentiments ou phénomènes affectifs. [less ▲]

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See detailConscience et représentation. Débats récents en philosophie de l'esprit
Dewalque, Arnaud ULg; Gauvry, Charlotte ULg

E-print/Working paper (2015)

Introduction for a book on representationalism I am co-editing with Charlotte Gauvry.

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See detailL-surface and V-valley for optimal anisotropic 2D smoothing
Frasso, Gianluca ULg; Paul, Eilers

E-print/Working paper (2014)

We present the L-surface as an attractive generalization of the L-curve framework for the selection of the optimal smoothing parameters in two dimensional applications. It preserves the desirable features ... [more ▼]

We present the L-surface as an attractive generalization of the L-curve framework for the selection of the optimal smoothing parameters in two dimensional applications. It preserves the desirable features of its unidimensional analogous. The optimal amount of smoothing is indicated by the pair of parameters located in the point of maximum (Gaussian) curvature. Locate this point on a discrete parametric surface can be not straightforward. We introduce the V-valley as a simplified selection criterion based on distance minimization. [less ▲]

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See detailMulti-period vehicle assignment problem with stochastic load availability
Crama, Yves ULg; Pironet, Thierry ULg

E-print/Working paper (2014)

In this research, we want to investigate optimization techniques for a generic load assignment problem including a limited fleet of vehicles within a full-truck-load (FTL) multi-period setting including ... [more ▼]

In this research, we want to investigate optimization techniques for a generic load assignment problem including a limited fleet of vehicles within a full-truck-load (FTL) multi-period setting including forecasts on load availability. Several policies are generated from simple heuristics through state of the art approaches such as consensus and restricted expectation algorithms up to the optimization of a subtree of scenarios. Moreover, myopic and a-posteriori deterministic optimizations (including no or fully revealed information) set bounds for policies performance comparisons. Tests are performed for different graphs sizes and sparsity, several distribution laws and number of loads. Performances are compared statistically over paired samples. The robustness of performing policies against a false valuation of the probability distribution is also analyzed. [less ▲]

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See detailIdentifying the best technical trading rule: a .632 bootstrap approach.
Hambuckers, julien ULg; Heuchenne, Cédric ULg

E-print/Working paper (2014)

In this paper, we are interested in estimating the out-of-sample predictive ability of a set of trading rules. Usually, this ability is estimated using a rolling-window sample-splitting scheme, true out ... [more ▼]

In this paper, we are interested in estimating the out-of-sample predictive ability of a set of trading rules. Usually, this ability is estimated using a rolling-window sample-splitting scheme, true out-of-sample data being rarely available. We argue that this method makes a poor use of the available information and creates data mining possibilities. Instead, we propose an alternative bootstrap approach, based on the .632 bootstrap principle, that makes a full use of the data at hand and decreases data mining occasions. This method enables to compute a robust estimator of the out-of-sample predictive ability of a trading rule by generating both in-sample and out-of-sample bootstrap data. These data are later used to measure the performance over a large range of scenarios. We illustrate our methodology on IBM and Microsoft daily stock prices, where we compare 11 trading rules specifications, with a total of 11,668 parametrizations. Our results showed that the out-of-sample performance of all rules decreases strongly compared to the in-sample performance. For the datasets considered, two different filter rule specifications have the highest out-of-sample mean excess returns. However, all tested rules have mean excess returns close or below zero, suggesting that none of these rules can truly generate a profit, nor beat a simple buy-and-hold strategy. [less ▲]

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See detailRéveillez-vous, le monde vous attend…
Gerkens, Jean-François ULg; Faymonville, Marie-Elisabeth ULg; Destiné, Jacques ULg et al

E-print/Working paper (2014)

Par-delà le brouillard des temps présents, un message d’optimisme, de volontarisme, de foi en l’avenir et en la vie, conduisant à sept principes, ou suggestions d’action, faciles à mettre en œuvre.

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See detailEmbargo russe sur les aliments européens : l'Europe doit montrer l'exemple
Habran, Maxime ULg

E-print/Working paper (2014)

Cette note a pour but d’apporter des éclaircissements sur les mesures en matière de politique agricole commune prises par l’Union européenne

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See detailDe la crise à l’entreprise, en passant par toi…
Choffray, Jean-Marie ULg

E-print/Working paper (2014)

De la crise à l’entreprise, en passant par toi… est une invitation à l’action, à la prise de responsabilité, à la création responsable de valeur économique et à la recherche obstinée de croissance ... [more ▼]

De la crise à l’entreprise, en passant par toi… est une invitation à l’action, à la prise de responsabilité, à la création responsable de valeur économique et à la recherche obstinée de croissance rentable. Oui! Notre monde vient d’échapper à un effondrement systémique dont 1929 n’aurait constitué qu’un aimable préambule. Oui ! L’entreprise est le seul acteur social créateur de richesse économique et la seule solution au mal qui se répand. Oui ! Il est extrêmement difficile de changer quoi que ce soit sur terre et d’apprendre à dire « non ! » En cas d’échec, le coût est connu : licenciement, exil, condamnation à mort ! [less ▲]

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See detailRecueil de réglementation interne des principaux partis allemands, belges et britanniques
Bouhon, Frédéric ULg

E-print/Working paper (2014)

Le présent recueil compile des extraits de la réglementation interne des principaux partis allemands, belges et britanniques. Cette documentation vient principalement appuyer le chapitre 1er de la ... [more ▼]

Le présent recueil compile des extraits de la réglementation interne des principaux partis allemands, belges et britanniques. Cette documentation vient principalement appuyer le chapitre 1er de la deuxième partie de notre étude sur le droit électoral et le principe d’égalité (à paraître en septembre 2014 aux éditions Bruylant) dans laquelle nous avons notamment étudié une partie du droit interne de certaines formations politiques. [less ▲]

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See detailShort Prime Quadratizations of Cubic Negative Monomials
Crama, Yves ULg; Rodriguez Heck, Elisabeth ULg

E-print/Working paper (2014)

Pseudo-Boolean functions naturally model problems in a number of different areas such as computer science, statistics, economics, operations research or computer vision, among others. Pseudo-Boolean ... [more ▼]

Pseudo-Boolean functions naturally model problems in a number of different areas such as computer science, statistics, economics, operations research or computer vision, among others. Pseudo-Boolean optimization (PBO) is NP-hard, even for quadratic polynomial objective functions. However, much progress has been done in finding exact and heuristic algorithms for the quadratic case. Quadratizations are techniques aimed at reducing a general PBO problem to a quadratic polynomial one. Quadratizing single monomials is particularly interesting because it allows quadratizing any pseudo-Boolean function by termwise quadratization. A characterization of short quadratizations for negative monomials has been provided. In this report we present a proof of this characterization for the case of cubic monomials, which requires a different analysis than the case of higher degree. [less ▲]

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See detailOptimization of the service start time for an elementary shortest path problem with time windows
Arda, Yasemin ULg; Crama, Yves ULg; Kucukaydin, Hande ULg

E-print/Working paper (2014)

We investigate an elementary shortest path problem with resource constraints where a single capacitated vehicle, initially located at a depot, must serve a set of customers while respecting their ... [more ▼]

We investigate an elementary shortest path problem with resource constraints where a single capacitated vehicle, initially located at a depot, must serve a set of customers while respecting their individual time windows. When the vehicle visits a customer, it delivers the customer's demand and collects a revenue in return for the delivery. The vehicle can start its trip at any desired time. The transportation cost is a function of both the total distance traveled and the duration of the assigned trip. The objective is to determine the service start time from the depot, the subset of customers to be served, and the trip to be performed so as to minimize the total loss, which is calculated as the di erence between the transportation cost and the revenue collected from the customers. We develop two exact dynamic programming algorithms which can deal with an in nite number of Pareto-optimal states arising from the fact that the starting time and the duration of the trip act like continuous decision variables. We report computational results obtained with these algorithms and with a faster heuristic for the elementary shortest path problem. We also examine the performance of these algorithms when they are used to solve the pricing subproblem arising in the framework of a column generation algorithm for a related vehicle routing problem with time windows. [less ▲]

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See detailEconomic Statistical Design of the VP( X) ̅ Control Charts for Monitoring a Process under Non-normality
Seif, Asghar; Faraz, Alireza ULg; Saniga, Erwin

E-print/Working paper (2014)

Recent studies proved that variable parameters (VP) X ̅ control charts not only detects process mean shifts quicker than the classical X ̅ control chart but also has better economic properties ... [more ▼]

Recent studies proved that variable parameters (VP) X ̅ control charts not only detects process mean shifts quicker than the classical X ̅ control chart but also has better economic properties. Furthermore, like most papers in control chart design, the fundamental assumption is that process data are normally distributed. Nevertheless, process quality variables may not be normal in application. In this paper, we investigate the economic statistical design of the VP X ̅ control chart when the underlying process distribution is non-normal. We illustrate the design procedure and perform a sensitivity analysis on the process and cost parameters based upon the degrees of skewness and kurtosis of the population using an industrial application. [less ▲]

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See detailCeci n’est pas un conseil !
Choffray, Jean-Marie ULg

E-print/Working paper (2014)

La « Grande Récession de 2008 » a un mérite. Un seul ! Elle a rendu public le fait que personne ne savait exactement ce qui s’était passé, ni ce qui se passait. Pourquoi une telle crise de confiance avait ... [more ▼]

La « Grande Récession de 2008 » a un mérite. Un seul ! Elle a rendu public le fait que personne ne savait exactement ce qui s’était passé, ni ce qui se passait. Pourquoi une telle crise de confiance avait-elle vu le jour ? Quelles en seraient les conséquences ? Toutes et tous se sont trompés, y compris les meilleurs. Même celles et ceux qui étaient convaincus d’avoir raison ! Plus que jamais, l’incertitude, la saine et souveraine incertitude, garantit la liberté de l’investisseur... et du professeur ! [less ▲]

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See detailLettre d'information trimestrielle n° 14 du projet DACEFI 2
Meunier, Quentin; Moumbogou, Carl; Boldrini, Sylvie et al

E-print/Working paper (2014)

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See detailThe Macroeconomics of PAYG Pension Schemes in an Aging Society
Artige, Lionel ULg; Cavenaile, Laurent; Pestieau, Pierre ULg

E-print/Working paper (2014)

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See detailAn Ant Colony System for Responsive Dynamic Vehicle Routing
Schyns, Michael ULg

E-print/Working paper (2014)

We present an algorithm based on an Ant Colony System to deal with a broad range of Dynamic Capacitated Vehicle Routing Problems with Time Windows, (partial) Split Delivery and Heterogeneous fleets ... [more ▼]

We present an algorithm based on an Ant Colony System to deal with a broad range of Dynamic Capacitated Vehicle Routing Problems with Time Windows, (partial) Split Delivery and Heterogeneous fleets (DVRPTWSD). Besides the traditional distance criterion, we address the important case of responsiveness. Responsiveness is defined here as completing a delivery as soon as possible, within the time window, such that the client or the truck may restart its activities. This is crucial for many production or service activities in different fields: express parcel deliveries, taxi services, Just in Time production, express repair services, medical care, petrol station replenishment, etc. We develop an interactive web-based solution to allow dispatchers to take new information into account in real-time. The algorithm and its parametrization were tested on real and artificial instances. We first illustrate our approach with a problem submitted by Liege Airport, the 8th biggest cargo airport in Europe. The goal is to develop a decision system to optimize the journey of the refueling trucks. We then consider some classical VRP benchmarks with extensions for more complex problems. [less ▲]

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See detailA new methodological approach for error distributions selection in Finance
Hambuckers, julien ULg; Heuchenne, Cédric ULg

E-print/Working paper (2014)

In this article, we propose a robust methodology to select the most appropriate error distribution candidate, in a classical multiplicative heteroscedastic model. In a first step, unlike to the ... [more ▼]

In this article, we propose a robust methodology to select the most appropriate error distribution candidate, in a classical multiplicative heteroscedastic model. In a first step, unlike to the traditional approach, we don't use any GARCH-type estimation of the conditional variance. Instead, we propose to use a recently developed nonparametric procedure (Mercurio and Spokoiny, 2004): the Local Adaptive Volatility Estimation (LAVE). The motivation for using this method is to avoid a possible model misspecification for the conditional variance. In a second step, we suggest a set of estimation and model selection procedures (Berk-Jones tests, kernel density-based selection, censored likelihood score, coverage probability) based on the so-obtained residuals. These methods enable to assess the global fit of a given distribution as well as to focus on its behavior in the tails. Finally, we illustrate our methodology on three time series (UBS stock returns, BOVESPA returns and EUR/USD exchange rates). [less ▲]

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See detailProtecting Assets Under Non-Parametric Market Conditions
Choffray, Jean-Marie ULg; Pahud de Mortanges, Charles ULg

E-print/Working paper (2014)

Under non-parametric market conditions, investors usually become more concerned about the return of their money than about the return on their money. Protecting assets becomes the surest if not the only ... [more ▼]

Under non-parametric market conditions, investors usually become more concerned about the return of their money than about the return on their money. Protecting assets becomes the surest if not the only path to survival and growth. High frequency trading systems, over leveraged shadow entities, flash crashes, and stealth central bank actions, to name a few, contribute to create a “Rumsfeldian” type of world in which decision makers have to cope not only with “Known knowns” – things they know that they know – but also with “Unknown unknowns” – things they don’t know that they don’t know! The goal of this paper is to explore such a conceptual model of the “Unknown” and to derive from it a concise and coherent set of battle-tested heuristics aimed at designing effective investment strategies to protect assets. [less ▲]

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See detailLes determinants des Price-Earnings ratios en Europe
Lambert, Marie ULg; Lenglois, Julien ULg; Streel, Alexandre ULg et al

E-print/Working paper (2014)

Méthode largement employée en matière d’évaluation d’entreprise, l’analyse dite comparative s’appuie sur une estimation de la valeur des entreprises selon un multiple de leur agrégat financier. Aussi ... [more ▼]

Méthode largement employée en matière d’évaluation d’entreprise, l’analyse dite comparative s’appuie sur une estimation de la valeur des entreprises selon un multiple de leur agrégat financier. Aussi appelée ‘méthode des pairs’, les multiples sont définis sur base d’un échantillon d’entreprises considérées comme comparable en termes de croissance et de risque. Le secteur est généralement retenu en pratique comme critère sous-tendant la croissance et le profil de risque opérationnel de l’entreprise. L’analyse menée dans cet article démontre l’importance des fondamentaux tels que la croissance, le risque et le taux de distribution des bénéfices dans la définition des pairs et donc de la valeur des entreprises. Sur base d’un échantillon des 100 entreprises cotées sur l’EURONEXT, entreprises les plus capitalisées et liquides, l’étude met en évidence un impact différencié de ces déterminants selon les conditions économiques. Les conséquences de notre analyse sont multiples. Premièrement, notre étude témoigne de l’importance des variables telles que le profil de risque et les perspectives croissance pour la sélection des pairs. Notre approche permet par ailleurs d’appréhender la valeur des entreprises sur base de leurs propres fondamentaux, corrigeant ainsi la méthode des multiples ‘sectoriels’ pour les différences qui subsistent au sein des sous-jacents de la valeur. Finalement, cet article nourrit une discussion quant à l’impact de la finance comportementale sur la valorisation de l’entreprise de par l’impact différencié des fondamentaux sur la valeur des entreprises au cours du temps. [less ▲]

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See detailTentatives de réflexion sémiotique et psychanalytique au sujet du voile islamique
Demoulin, Laurent ULg

E-print/Working paper (2014)

La sémiotique et la psychanalyse sont peut-être de nature à enrichir le débat sur l'interdiction du voile islamique dans les lieux publics.

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See detailMultivariate coefficients of variation: comparison and influence functions
Aerts, Stéphanie ULg; Haesbroeck, Gentiane ULg; Ruwet, Christel ULg

E-print/Working paper (2014)

In the univariate setting, coefficients of variation are well known and used to compare the variability of populations characterized by variables expressed in different units or having really different ... [more ▼]

In the univariate setting, coefficients of variation are well known and used to compare the variability of populations characterized by variables expressed in different units or having really different means. When dealing with more than one variable, the use of such a relative dispersion measure is much less common even though several generalizations of the coefficient of variation to the multivariate setting have been introduced in the literature. In this paper, the lack of robustness of the sample versions of the multivariate CV's is illustrated by means of influence functions and a robust counterpart based on the Minimum Covariance Determinant (MCD) estimator is advocated. Then, focusing on two of the considered multivariate CV's, a diagnostic tool based on their influence functions is derived and its efficiency in detecting observations having an unduly large effect on variability is illustrated on a real-life data set. The influence functions are also used to compute asymptotic variances under elliptical distributions, yielding approximate confidence intervals. Finally, simulations are conducted in order to compare the performance of the classical and robust multivariate CV's in a finite sample setting. As expected, when the data are normally distributed, the classical estimator performs better than the robust counterpart based on the MCD estimator, while the reverse is true when the data are contaminated. [less ▲]

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See detailExamining the Effect of Earnings Management on Bid-Ask Spread and Market Liquidity
Sougné, Danielle ULg; Ajina, Aymen ULg

E-print/Working paper (2014)

The main purpose of this paper is to argue the extent that earnings management lowers liquidity. It should increase information asymmetry and impair trading liquidity. Using a sample of French firms from ... [more ▼]

The main purpose of this paper is to argue the extent that earnings management lowers liquidity. It should increase information asymmetry and impair trading liquidity. Using a sample of French firms from 2008 to 2011, we find that firms that manage earnings have wider bid-ask spreads. Our results are robust for both of two well established measures of market liquidity. Therefore the empirical results indicate that firms that exhibit greater earnings management are associated with lower market liquidity. These findings are in line with adverse selection and shed light on the role corporate governance devices can play in the consideration of shareholder interest’s protection, which leads to improved stock market liquidity levels. [less ▲]

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See detailProposition de révisions de l'arrêté n° 018/MEF/SG/DGF/DFCOM du 31 janvier 2013 fixant les procédures d'attribution et de gestion des forêts communautaires
Moumbogou, Carl; Boldrini, Sylvie; Morin, Amélie et al

E-print/Working paper (2014)

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See detailBott type periodicity for the higher octonions
Kreusch, Marie ULg

E-print/Working paper (2014)

We study the series of complex nonassociative algebras $\bbO_n$ and real nonassociative algebras $\bbO_{p,q}$ introduced in~\cite{MGO2011}. These algebras generalize the classical algebras of octonions ... [more ▼]

We study the series of complex nonassociative algebras $\bbO_n$ and real nonassociative algebras $\bbO_{p,q}$ introduced in~\cite{MGO2011}. These algebras generalize the classical algebras of octonions and Clifford algebras. The algebras $\bbO_{n}$ and $\bbO_{p,q}$ with $p+q=n$ have a natural $\Z_2^n$-grading, and they are characterized by cubic forms over the field $\Z_2$. We establish a periodicity for the algebras~$\bbO_{n}$ and $\bbO_{p,q}$ similar to that of the Clifford algebras $\mathrm{Cl}_{n}$ and~$\mathrm{Cl}_{p,q}$. [less ▲]

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See detailLettre d'information trimestrielle n° 13 du projet DACEFI 2
Meunier, Quentin; Moumbogou, Carl; Boldrini, Sylvie et al

E-print/Working paper (2014)

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See detailLettre d'Information N° 12 projet Dacefi
Meunier, Quentin; Mezui Mba, C.; Boldrini, Sylvie et al

E-print/Working paper (2014)

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See detailExperimental Study and Statistical Modeling of an Injection Scroll Compressor Operating with R407c.
Quoilin, Sylvain ULg

E-print/Working paper (2014)

This working paper describes an experimental study carried out on a refrigeration scroll compressor with and without vapour injection. The test rig designed for that purposed allows evaluating the ... [more ▼]

This working paper describes an experimental study carried out on a refrigeration scroll compressor with and without vapour injection. The test rig designed for that purposed allows evaluating the performance over a wide range of operating conditions, by varying the supply pressure, the injection pressure, the exhaust pressure, the supply superheating and the injection superheating. 97 Steady-state points are measured, with a maximum isentropic efficiency of 64.1% and a maximum consumed electrical power of 13.1 kW. A critical analysis of the experimental results is then carried out to evaluate the quality of the data using a machine learning method. This method based on Gaussian Processes regression, is used to build a statistical operating map of the compressor as a function of the different inputs. This statistical operating map can then be compared to the experimental data points to evaluate their accuracy. [less ▲]

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See detailNonparametric regression with cross-sectional data: an alternative to conditional product-limit estimators
Heuchenne, Cédric ULg; Laurent, Géraldine ULg

E-print/Working paper (2014)

Suppose the random vector (X,Y) satisfies the nonparametric regression model Y=m(X)+varepsilon, where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions and the error varepsilon ... [more ▼]

Suppose the random vector (X,Y) satisfies the nonparametric regression model Y=m(X)+varepsilon, where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions and the error varepsilon has zero mean and finite variance conditionally on X=x. The pair (X,Y) is obtained by cross-sectional sampling involving left-truncated and right-censored responses. The considered model is completely nonparametric but the conditional truncation distribution is assumed to be known. The novelty of this work is twofold: first, it extends the results on cross-sectional data to the conditional case and second, it generalizes the length bias results in the conditional case to right censoring and to any truncation distribution. New estimators for m(.) and sigma²(.) are constructed and relevant tools are used to quickly provide the main asymptotic properties for this kind of estimators. Extensive simulations are carried out and show that the new estimators outperform classical nonparametric estimators for left-truncated and right-censored data (when the truncation model is known). Finally, a data set on the mortality of diabetics is analyzed. [less ▲]

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See detailIntentionality as Disposition
Boccaccini, Federico ULg

E-print/Working paper (2014)

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See detailLes portfolio : vers une évaluation plus intégrée et plus cohérente avec la notion complexe de compétence
Poumay, Marianne ULg; Maillart, Christelle ULg

E-print/Working paper (2014)

Ce chapitre prend résolument le parti du témoignage et construit sur l’expérience des auteures. Il choisit quelques référents théoriques, qu’il illustre ensuite par deux expériences ciblées, l’une chez ... [more ▼]

Ce chapitre prend résolument le parti du témoignage et construit sur l’expérience des auteures. Il choisit quelques référents théoriques, qu’il illustre ensuite par deux expériences ciblées, l’une chez les étudiants en logopédie/orthophonie et l’autre chez les étudiants en pédagogie de l’enseignement supérieur, deux programmes de l’Université de Liège. Il conclut sur quelques réflexions et perspectives. [less ▲]

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See detailEstimation of the error distribution in nonparametric regression with cross-sectional data
Heuchenne, Cédric ULg; Laurent, Géraldine ULg

E-print/Working paper (2014)

In this article, we study the nonparametric regression model Y=m(X)+varepsilon where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions, and the error varepsilon has zero mean ... [more ▼]

In this article, we study the nonparametric regression model Y=m(X)+varepsilon where m(x)=E[Y|X=x] and sigma²(x)=Var[varepsilon|X=x] are unknown smooth functions, and the error varepsilon has zero mean and finite variance conditionally on X=x. The problem consists in estimating the cumulative distribution function of the error in a nonparametric way when the couple (X,Y) is obtained by cross-sectional sampling while the positive response Y can be right-censored. We propose a new estimator for the error distribution function based on the estimators of m(.) and sigma²(.) described in Heuchenne and Laurent 2014. A bootstrap procedure is developed to solve the critical problem of the smoothing parameter choice. We assess the performance of the proposed estimator through simulations. Finally, a data set based on the mortality of diabetics is analyzed. (Heuchenne Cédric and Laurent Géraldine, Nonparametric regression with cross-sectional data: an alternative to conditional product-limit estimators, 2014) [less ▲]

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See detailLa psychologie morale de Brentano
Boccaccini, Federico ULg

E-print/Working paper (2014)

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See detailThe role of segmentation and investor recognition trough the lens of cross-listing activity
Mouchette, Xavier ULg; Carrieri, Francesca; Muller, Aline ULg

E-print/Working paper (2014)

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See detailTowards robust GWAS/GWAI protocol development for epistasis detection in context of real-life datasets
Bessonov, Kyrylo ULg

E-print/Working paper (2014)

The genome-wide association and interaction studies are a common practice these days but the correct application of statistical methods and workflows that consciously select best data processing ... [more ▼]

The genome-wide association and interaction studies are a common practice these days but the correct application of statistical methods and workflows that consciously select best data processing strategies is often missing in many GWA studies. Nevertheless given the multitude of such studies there is little consistency and consensus in data processing workflows and quality control steps. Data selection and filtering is often overlooked or poorly documented. Many times the default settings are blindly used disregarding any adjustments and/or optimizations under the context of specific dataset. In present study we want to bring awareness of paying a closer attention to parameter selection in genome-wide association interaction studies (GWAI). We had tested the impact of LD filtering, selection of epistasis algorithms (BOOST, MB-MDR) and marker selection and prioritization strategies on the final results variability under the context of the Ankylosin Spondolytis (AS) dataset obtained from WTCCC2 [1]. [less ▲]

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Peer Reviewed
See detailL'expérience internationale étudiante: un atout pour une carrière internationale?
Robert, Jocelyne ULg; Carrabs, Vincenzo

E-print/Working paper (2014)

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See detailSize Matters, Book Value does not! The Fama-French empirical CAPM revisited
Lambert, Marie ULg; Hübner, Georges ULg

E-print/Working paper (2014)

The Fama and French (F&F) factors do not reliably estimate the size and book-to-market effects. Our paper shows that the former has been underestimated in the US market while the latter overestimated. We ... [more ▼]

The Fama and French (F&F) factors do not reliably estimate the size and book-to-market effects. Our paper shows that the former has been underestimated in the US market while the latter overestimated. We do so by replacing F&F’s independent rankings by the conditional ones introduced by Lambert and Hübner (2013), over which we improve the sorting procedure. This new specification better reflects the properties of the individual risk premiums. We emphasize a much stronger size effect than conventionally documented. As a major related outcome, the alternative risk factors deliver less specification errors when used to price passive investment indices [less ▲]

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See detailAn assessment of cross-listed firms’ diversification potential
Mouchette, Xavier ULg; Muller, Aline ULg

E-print/Working paper (2014)

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See detailA Supervised Machine Learning Approach to Variable Branching in Branch-And-Bound
Marcos Alvarez, Alejandro ULg; Louveaux, Quentin ULg; Wehenkel, Louis ULg

E-print/Working paper (2014)

We present in this paper a new approach that uses supervised machine learning techniques to improve the performances of optimization algorithms in the context of mixed-integer programming (MIP). We focus ... [more ▼]

We present in this paper a new approach that uses supervised machine learning techniques to improve the performances of optimization algorithms in the context of mixed-integer programming (MIP). We focus on the branch-and-bound (B&B) algorithm, which is the traditional algorithm used to solve MIP problems. In B&B, variable branching is the key component that most conditions the efficiency of the optimization. Good branching strategies exist but are computationally expensive and usually hinder the optimization rather than improving it. Our approach consists in imitating the decisions taken by a supposedly good branching strategy, strong branching in our case, with a fast approximation. To this end, we develop a set of features describing the state of the ongoing optimization and show how supervised machine learning can be used to approximate the desired branching strategy. The approximated function is created by a supervised machine learning algorithm from a set of observed branching decisions taken by the target strategy. The experiments performed on randomly generated and standard benchmark (MIPLIB) problems show promising results. [less ▲]

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See detailParametric conditional variance estimation in location-scale models with censored data
Heuchenne, Cédric ULg; Laurent, Géraldine ULg

E-print/Working paper (2014)

Suppose the random vector (X,Y) satisfies the regression model Y=m(X)+sigma(X)*varepsilon, where m(.)=E(Y|.), sigma²(.)=Var(Y|.) belongs to some parametric class {sigma _theta(.): theta in Theta} and ... [more ▼]

Suppose the random vector (X,Y) satisfies the regression model Y=m(X)+sigma(X)*varepsilon, where m(.)=E(Y|.), sigma²(.)=Var(Y|.) belongs to some parametric class {sigma _theta(.): theta in Theta} and varepsilon is independent of X. The response Y is subject to random right censoring and the covariate X is completely observed. A new estimation procedure is proposed for sigma_theta(.) when m(.) is unknown. It is based on nonlinear least squares estimation extended to conditional variance in the censored case. The consistency and asymptotic normality of the proposed estimator are established. The estimator is studied via simulations and an important application is devoted to fatigue life data analysis. [less ▲]

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Peer Reviewed
See detailStatistically Bundled Shewhart Control Charts for Monitoring Delivery Chains Systems
Foster, Earnest; Faraz, Alireza ULg; Heuchenne, Cédric ULg

E-print/Working paper (2014)

Continuous monitoring of Delivery Time variables by means of control charts in a delivery chain is a very recent application of Statistical Process Control (SPC) to the service sector. The aim of the ... [more ▼]

Continuous monitoring of Delivery Time variables by means of control charts in a delivery chain is a very recent application of Statistical Process Control (SPC) to the service sector. The aim of the proposed method is to provide supply chain decision makers with an easy to be managed tool monitoring the current functioning state of the delivery chain. The implementation of SPC control charts makes it possible to limit over-corrections to false alarm conditions and to maintain at an acceptable level the safety stock, with a consequent reduction of the overall management costs of the delivery chain. An illustrative example shows the proposed control chart implementation in a real delivery chain. [less ▲]

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Peer Reviewed
See detailCan meandering flows in shallow rectangular reservoir be modelled with the 2D shallow water equations?
Peltier, Yann ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

E-print/Working paper (2014)

In this article, the ability of the 2D shallow water equations to model meandering flows in shallow rectangular reservoirs is discussed. Four meandering flows, of various shallowness, were modelled using ... [more ▼]

In this article, the ability of the 2D shallow water equations to model meandering flows in shallow rectangular reservoirs is discussed. Four meandering flows, of various shallowness, were modelled using the academic flow model WOLF 2D, which includes a depth-averaged k- model accounting for the horizontal and vertical turbulent length-scales. The bottom friction was modelled with the Colebrook-White formula and different roughness heights were considered. A Proper Orthogonal Decomposition (POD) was applied to the simulation results to extract the behaviour of the main structures responsible for the meandering flow. The same POD analysis was also performed for the reference experimental flow fields, obtained by Large-Scale Particle Image Velocimetry. The first two POD modes obtained from the numerical simulations assuming a smooth bottom are in good agreement with the experimental modes in terms of energy, as well as temporal and spatial variations, whatever the shallowness. In contrast, the remaining simulated modes are not well rendered. The effect of an increased roughness height in the simulations is finally discussed. It leads to an improved reproduction of the first two modes and of the following modes, except when significant viscous effects govern in the flow. [less ▲]

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See detailL’intervention militaire internationale au Kosovo
Pierre, Alexia ULg

E-print/Working paper (2014)

This paper aims first to explore the international armed intervention in Kosovo, formalized through the Allied Force Operation headed by the Nato. A second part is dedicated to the legal aspects of this ... [more ▼]

This paper aims first to explore the international armed intervention in Kosovo, formalized through the Allied Force Operation headed by the Nato. A second part is dedicated to the legal aspects of this intervention regarding the international norms. [less ▲]

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Peer Reviewed
See detailAcoustic velocity measurements for evaluating bed stability parameters
Duma, Diana ULg; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

E-print/Working paper (2014)

Assessing the stability of riverbeds is a major issue in many aspects of hydraulic and river engineering. Although the Shields diagram remains the most widely accepted approach, it faces a number of ... [more ▼]

Assessing the stability of riverbeds is a major issue in many aspects of hydraulic and river engineering. Although the Shields diagram remains the most widely accepted approach, it faces a number of shortcomings. In particular, its ability to reflect the influence of turbulence on sediment motion becomes questionable when it is applied under strongly non-uniform flow conditions, which are of high practical relevance in hydraulic engineering. Therefore, new approaches were proposed, which relate the degree of damage of gravel beds to so-called bed stability parameters depending explicitly on the local intensity of flow turbulence. However, these new bed stability parameters are much more demanding in term of detailed description of the flow field and, in all studies so far, they were estimated based only on Laser Doppler Velocimetry or Particle Image Velocimetry. Here, we investigate for the first time the suitability of acoustic velocity measurement techniques to evaluate these bed stability parameters. The experiments focus on smooth-to-rough transitions and a quasi-uniform configuration is used as a reference. Flow velocities were obtained using two complementary devices: an Ultrasonic Velocity Profiler and a 3D Acoustic Doppler Velocimeter. The new experimental results show that relatively robust estimates of the new stability parameters can be obtained from the 3D acoustic measurements. [less ▲]

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See detailThe Airline Container Loading Problem with Pickup and Delivery
Lurkin, Virginie ULg; Schyns, Michael ULg

E-print/Working paper (2013)

The present paper looks into the problem of optimizing the loading of a set of containers and pallets into cargo aircraft serving multiple airports. Due to the pickup and delivery operations occurring at ... [more ▼]

The present paper looks into the problem of optimizing the loading of a set of containers and pallets into cargo aircraft serving multiple airports. Due to the pickup and delivery operations occurring at intermediate airports, this problem is simultaneously a weight and balance problem and a sequencing problem. Our objective is to minimize fuel and handling operations costs. This problem is shown to be NP-hard. We resort to a mixed integer linear program. On the basis of a professional partner's real-world data, TNT Airways, we perform numerical experiments using a standard B&C library. This approach yields better solutions than traditional manual planning, which results in substantial cost savings. [less ▲]

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See detailQuadratization of symmetric pseudo-Boolean functions
Anthony, Martin; Boros, Endre; Crama, Yves ULg et al

E-print/Working paper (2013)

A pseudo-Boolean function is a real-valued function $f(x)=f(x_1,x_2,\ldots,x_n)$ of $n$ binary variables; that is, a mapping from $\{0,1\}^n$ to ${\bbr}$. For a pseudo-Boolean function $f(x)$ on $\{0,1 ... [more ▼]

A pseudo-Boolean function is a real-valued function $f(x)=f(x_1,x_2,\ldots,x_n)$ of $n$ binary variables; that is, a mapping from $\{0,1\}^n$ to ${\bbr}$. For a pseudo-Boolean function $f(x)$ on $\{0,1\}^n$, we say that $g(x,y)$ is a quadratization of $f$ if $g(x,y)$ is a quadratic polynomial depending on $x$ and on $m$ auxiliary binary variables $y_1,y_2,\ldots,y_m$ such that $f(x)= \min \{ g(x,y) : y \in \{0,1\}^m \} $ for all $x \in \{0,1\}^n$. By means of quadratizations, minimization of $f$ is reduced to minimization (over its extended set of variables) of the quadratic function $g(x,y)$. This is of some practical interest because minimization of quadratic functions has been thoroughly studied for the last few decades, and much progress has been made in solving such problems exactly or heuristically. A related paper initiated a systematic study of the minimum number of auxiliary $y$-variables required in a quadratization of an arbitrary function $f$ (a natural question, since the complexity of minimizing the quadratic function $g(x,y)$ depends, among other factors, on the number of binary variables). In this paper, we determine more precisely the number of auxiliary variables required by quadratizations of \emph{symmetric} pseudo-Boolean functions $f(x)$, those functions whose value depends only on the Hamming weight of the input $x$ (the number of variables equal to 1). [less ▲]

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See detailEstimation and approximation in multidimensional dynamics
Frasso, Gianluca ULg; Jaeger, Jonathan ULg; Lambert, Philippe ULg

E-print/Working paper (2013)

Differential equations (DEs) are commonly used to describe dynamic systems evolving in one (ordinary differential equations or ODEs) or in more than one dimensions (partial differential equations or PDEs ... [more ▼]

Differential equations (DEs) are commonly used to describe dynamic systems evolving in one (ordinary differential equations or ODEs) or in more than one dimensions (partial differential equations or PDEs). In real data applications the parameters involved in the DE models are usually unknown and need to be estimated from the available measurements together with the state function. In this paper, we present frequentist and Bayesian approaches for the joint estimation of the parameters and of the state functions involved in PDEs. We also propose two strategies to include differential (initial and/or boundary) conditions in the estimation procedure. We evaluate the performances of the proposed strategy on simulated and real data applications. [less ▲]

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See detailRevealed preference tests of collectively rational consumption behavior: formulations and algorithms
Talla Nobibon, Fabrice; Cherchye, Laurens; Crama, Yves ULg et al

E-print/Working paper (2013)

This paper focuses on revealed preference tests of the collective model of household consumption. We start by showing that the decision problems corresponding to testing collective rationality are {\sc np ... [more ▼]

This paper focuses on revealed preference tests of the collective model of household consumption. We start by showing that the decision problems corresponding to testing collective rationality are {\sc np}-complete. This makes the application of these tests problematic for (increasingly available) large(r) scale data sets. We then present two approaches to overcome this negative result. First, we introduce exact algorithms based on mixed-integer programming ({\sc mip}) formulations of the collective rationality tests, which can be usefully applied to medium sized data sets. Next, we propose simulated annealing heuristics, which allow for efficient testing of the collective model in the case of large data sets. We illustrate our methods by a number of computational experiments based on Dutch labor supply data. [less ▲]

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See detailLettre d'information trimestrielle du projet DACEFI 2 - Retour sur l'attribution des premières forêts communautaires du Gabon
Meunier, Quentin; Moumbogou, Carl; Morin, Amélie et al

E-print/Working paper (2013)

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See detailInvestir Ou Mourir ? Il Faut Choisir…
Choffray, Jean-Marie ULg

E-print/Working paper (2013)

Investir : c’est croire en l’avenir. C’est renoncer en partie au présent pour donner vie au futur. C’est tourner le dos aux « Bouffeurs d’espoir » et à l’illusoire confort du statu quo. Enfin, et surtout ... [more ▼]

Investir : c’est croire en l’avenir. C’est renoncer en partie au présent pour donner vie au futur. C’est tourner le dos aux « Bouffeurs d’espoir » et à l’illusoire confort du statu quo. Enfin, et surtout, c’est oser «Oser » ! La distance séparant le discours public de la performance économique avérée suffit à démontrer l’incompréhension des mécanismes de création de richesse de ceux qui sont censés en avoir la maîtrise et les mettre en œuvre. Il est peu de domaines où les illusions, et autres idées fausses, ont un succès tel qu’elles amènent l’observateur aguerri à s’interroger sur le profit que d’aucuns pourraient en tirer. L’objet de ce document est de partager le fruit d’une réflexion menée sur le thème de l’Investissement, forme proéminente et condition première de l’activité économique, au moment où certains s’interrogent sur son encadrement et cherchent à en limiter la liberté. [less ▲]

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See detailAn overview of the foundations' sector in Belgium
Mernier, Amélie ULg

E-print/Working paper (2013)

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Peer Reviewed
See detailQuelques considérations sur la présomption de titularité des droits d'auteur dans la loi du 30 juin 1994 relative au droit d'auteur et aux droits voisins.
Kouembeu Tagne, Jean Jacques ULg

E-print/Working paper (2013)

Nous avons choisi d'axer notre raisonnement sur la problématique de la présomption de titularité des droits d’auteur dans la loi du 30 juin 1994 relative au droit d'auteur et aux droits voisins. Que ... [more ▼]

Nous avons choisi d'axer notre raisonnement sur la problématique de la présomption de titularité des droits d’auteur dans la loi du 30 juin 1994 relative au droit d'auteur et aux droits voisins. Que signifie-t-elle ? Quelles sont les conditions nécessaires à sa mise en œuvre ? Comment les démonter ? [less ▲]

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See detailUne leçon de Poker Menteur
Choffray, Jean-Marie ULg

E-print/Working paper (2013)

L’évolution de la situation de la société Exide Technologies (Nasdaq : XIDE) offre à l’investisseur potentiel une superbe leçon de « Poker Menteur ». Dans la mesure où les marchés ne produisent pas ... [more ▼]

L’évolution de la situation de la société Exide Technologies (Nasdaq : XIDE) offre à l’investisseur potentiel une superbe leçon de « Poker Menteur ». Dans la mesure où les marchés ne produisent pas souvent ce type de « Quasi-expérience », j’ai décidé d’en reconstruire l’histoire et d’en suivre le développement. En partageant ces observations, mon objectif est de transformer une décision d’investissement réalisée dans des « Conditions Extrêmes » en une expérience susceptible d’être conceptualisée et transmise à d’autres. De plus, la solution à cette situation exceptionnelle pourrait constituer un cas d’école dans le domaine des partenariats public-privé à susciter dans le cadre de la transition énergétique d’un Etat ou d’une région. Temps réel oblige…, trois révisions de ce document sont prévues, en fin de semaine, dans le mois à venir. [less ▲]

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See detailApproximation Algorithms for Multi-Dimensional Vector Assignment Problems
Dokka, Trivikram; Crama, Yves ULg; Spieksma, Frits C.R.

E-print/Working paper (2013)

We consider a special class of axial multi-dimensional assignment problems called multi-dimensional vector assignment (MVA) problems. An instance of the MVA problem is defined by $m$ disjoint sets, each ... [more ▼]

We consider a special class of axial multi-dimensional assignment problems called multi-dimensional vector assignment (MVA) problems. An instance of the MVA problem is defined by $m$ disjoint sets, each of which contains the same number $n$ of $p$-dimensional vectors with nonnegative integral components, and a cost function defined on vectors. The cost of an $m$-tuple of vectors is defined as the cost of their component-wise maximum. The problem is now to partition the $m$ sets of vectors into $n$ $m$-tuples so that no two vectors from the same set are in the same $m$-tuple and so that the total cost of the $m$-tuples is minimized. The main motivation comes from a yield optimization problem in semi-conductor manufacturing. We consider two classes of polynomial-time heuristics for MVA, namely, hub heuristics and sequential heuristics, and we study their approximation ratio. In particular, we show that when the cost function is monotone and subadditive, hub heuristics, as well as sequential heuristics, have finite approximation ratio for every fixed $m$. Moreover, we establish better approximation ratios for certain variants of hub heuristics and sequential heuristics when the cost function is monotone and submodular, or when it is additive. We provide examples to illustrate the tightness of our analysis. Furthermore, we show that the MVA problem is APX-hard even for the case $m=3$ and for binary input vectors. Finally, we show that the problem can be solved in polynomial time in the special case of binary vectors with fixed dimension $p$. [less ▲]

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See detailLe pape François se trompe-t-il ?
Choffray, Jean-Marie ULg

E-print/Working paper (2013)

La crise de panique généralisée à laquelle nous avons assisté depuis 2007/2008 – pour reprendre l’analyse qu’en fait l’homme le mieux informé du monde, Ben Bernanke –, n’est rien d’autre que le double ... [more ▼]

La crise de panique généralisée à laquelle nous avons assisté depuis 2007/2008 – pour reprendre l’analyse qu’en fait l’homme le mieux informé du monde, Ben Bernanke –, n’est rien d’autre que le double d’une crise de confiance trouvant son origine dans l’accélération de l’information et la difficulté du pouvoir politique à en percevoir et à en accepter les conséquences. [less ▲]

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See detailLes FAQs du tableau de bord - Mythes et réalités du tableau de bord à l'ère de la mondialisation
Van Caillie, Didier ULg

E-print/Working paper (2013)

Ce document synthétise en 8 questions clés l'état de notre expérience en matière de conception et d'implémentation d'un tableau de bord dans une organisation, privée ou publique, grande ou petite. Les 8 ... [more ▼]

Ce document synthétise en 8 questions clés l'état de notre expérience en matière de conception et d'implémentation d'un tableau de bord dans une organisation, privée ou publique, grande ou petite. Les 8 questions abordées sont : 1. Qu’est-ce qu’un tableau de bord ? 2. Quelle est son utilité pour une organisation à l’ère de la mondialisation ? 3. Quels sont les prérequis à l’utilisation d’un tableau de bord ? 4. Faut-il un tableau de bord unique ou plusieurs tableaux de bord ? 5. Quels indicateurs intégrer au tableau de bord ? 6. Quelle forme donner à un tableau de bord ? 7. Quelle forme donner aux indicateurs retenus ? 8. Comment piloter le projet "Conception & implémentation d’un tableau de bord" ? [less ▲]

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See detailLa fin d'une époque...?
Choffray, Jean-Marie ULg

E-print/Working paper (2013)

Il est des moments exceptionnels dans la vie qui rappellent les lignes de fracture de l’histoire. C’est, peut-être, ce que notre monde moderne vit aujourd’hui. Dans ce document, et avant que nous ne ... [more ▼]

Il est des moments exceptionnels dans la vie qui rappellent les lignes de fracture de l’histoire. C’est, peut-être, ce que notre monde moderne vit aujourd’hui. Dans ce document, et avant que nous ne vivions ce qui pourrait être un printemps, ou un automne « chaud », il m’a paru utile de mettre un peu d’ordre dans mes observations sur « L’air du temps. » Pas d’autre ambition pour ce texte, donc, que de chercher à comprendre les événements passés, et de prendre date sur les nuages qui s’amoncellent ! [less ▲]

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Peer Reviewed
See detailRetour au travail après une longue absence...
Mairiaux, Philippe ULg

E-print/Working paper (2013)

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See detailLes nouvelles dispositions légales pour la récupération de bois abandonnés
Meunier, Quentin; Moumbogou, Carl; Vermeulen, Cédric ULg

E-print/Working paper (2013)

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See detailLa superposition des permis forestiers, des permis miniers et des futures forêts communautaires
Morin, Amélie; Moumbogou, Carl; Meunier, Quentin et al

E-print/Working paper (2013)

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See detailImpact of uncertainty in climate forcing on projections of the West Antarctic ice sheet over the 21st and 22nd centuries
Payne, A.J.; Cornford, S.L.; Martin, D.F. et al

E-print/Working paper (2013)

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See detailLettre d’information trimestrielle du projet Développement d’Alternatives Communautaires à l’Exploitation Forestière Illégale
Boldrini, Sylvie; Moumbogou; Meunier, Quentin et al

E-print/Working paper (2013)

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See detailEvolution de la ressource ligneuse et des stocks de carbone
Marien, Jean-Noel; Bisiaux, F.; Boulogne, M. et al

E-print/Working paper (2013)

Entre 2010 et 2012, une étude complexe a été menée pour apporter des éléments qualitatifs et quantitatifs fiables sur l’évolution de la ressource ligneuse sur le bassin d’approvisionnement en bois énergie ... [more ▼]

Entre 2010 et 2012, une étude complexe a été menée pour apporter des éléments qualitatifs et quantitatifs fiables sur l’évolution de la ressource ligneuse sur le bassin d’approvisionnement en bois énergie de Kinshasa. Cette étude pluridisciplinaire (Figure 1) a mobilisé l’analyse d’images satellites, la cartographie, les inventaires forestiers, la dendrométrie, des études sur la carbonisation traditionnelle et la compréhension des dynamiques sociales et économiques des zones d’étude. En plus d’analyser l’évolution de la couverture forestière sur la période de suivi (1984-2012), ce travail a permis de quantifier pour la première fois, sur des bases scientifiques et des méthodologies solides, les stocks de biomasse aérienne et de carbone ainsi que leur évolution. Après calage avec les standards REDD+, ces informations devraient se révéler très utiles dans la perspective des futurs projets REDD+ en Afrique centrale. Cette étude couvre une superficie de 900 000 ha située sur le plateau Batéké et au Bas Congo. La zone d’étude concerne près de 80% de l’approvisionnement total en bois énergie de l’agglomération de Kinshasa (Figure 2). [less ▲]

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See detailSocial Security and Economic Integration
Artige, Lionel ULg; Dedry, Antoine ULg; Pestieau, Pierre ULg

E-print/Working paper (2013)

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See detailReforming the Postal Universal Service
Gautier, Axel ULg; Poudou, Jean-Christophe

E-print/Working paper (2013)

The postal sector has undergone dramatic changes over the recent years under the double effect of ongoing liberalization and increased competition with alternative communication channels (e-substitution ... [more ▼]

The postal sector has undergone dramatic changes over the recent years under the double effect of ongoing liberalization and increased competition with alternative communication channels (e-substitution). As a result, the mail volume handled by the historical operator has declined sharply while the latter's ability to match the same standard of universal service may be under threat. Thus, a reform of the postal universal service is on the agenda. This paper examines possible reforming options ranging from keeping universal service within the postal sector to redefining universal service as spanning postal and electronic technologies. [less ▲]

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See detailBrentano’s empiricism and the refutation of a priori knowledge
Boccaccini, Federico ULg

E-print/Working paper (2013)

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See detailSoil apparent conductivity measurements for planning and analysis of agricultural experiments: A case study from Western-Thailand
Rudolph, Sebastian; Wongleecharoen, Chalemchart; Marchant, B. et al

E-print/Working paper (2013)

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See detailEstimation from cross-sectional data under a semiparametric truncation model
de Uña-Álvarez, Jacobo; Heuchenne, Cédric ULg; Laurent, Géraldine ULg

E-print/Working paper (2013)

Cross-sectional sampling is often used when investigating inter-event times, resulting in left-truncated and right-censored data. In this paper we consider a semiparametric truncation model in which the ... [more ▼]

Cross-sectional sampling is often used when investigating inter-event times, resulting in left-truncated and right-censored data. In this paper we consider a semiparametric truncation model in which the truncating variable is assumed to belong to a certain parametric family, while nothing is assumed on lifetime and censoring distributions. The novelty of this work is in the fact that it introduces estimators of this semiparametric model in the presence of censoring. Two alternative methods are considered, based on conditional and full likelihood considerations. Asymptotic representations of the estimators for the lifetime distribution are obtained, and their weak convergence is established. The finite sample performance of the new estimators is explored through simulations, and two real data illustrations are provided. One of the conclusions of our research is that both estimators perform better than Wang's NPMLE when the parametric family for the truncation variable is valid) in the sense of the integrated mean squared error, and that the full likelihood approach is preferable to the conditional likelihood approach for the estimation of the lifetime distribution but not necessarily for the estimation of the truncation distribution. [less ▲]

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See detailLa tolérance est coûteuse. On essaye l'intolérance ?
Jacquemain, Marc ULg

E-print/Working paper (2013)

Le texte a servi à présenter une conférence à des étudiants de bacheliers pédagogiques. Il rappelle, sur un ton informel, mais en essayant d'être rigoureux, la place et l'importance de la tolérance dans ... [more ▼]

Le texte a servi à présenter une conférence à des étudiants de bacheliers pédagogiques. Il rappelle, sur un ton informel, mais en essayant d'être rigoureux, la place et l'importance de la tolérance dans toute conception raisonnable de la vie en société. Il rappelle notamment que si la tolérance n'est pas une vertu "flamboyante", elle constitue un préalable indispensable à d'autres modalités plus exigeantes du vivre ensemble [less ▲]

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Peer Reviewed
See detailL’appropriation discursive et pratique du concept de développement durable par des GACEURS et des bénévoles/travailleurs du commerce équitable, vers un imaginaire critique partagé ?
Thys, Séverine ULg

E-print/Working paper (2013)

Ce Working Paper interroge l’existence d’un référentiel critique et argumentatif commun à des initiatives d’Economie Sociale du secteur alimentaire. En utilisant l’appareillage théorique de la « ... [more ▼]

Ce Working Paper interroge l’existence d’un référentiel critique et argumentatif commun à des initiatives d’Economie Sociale du secteur alimentaire. En utilisant l’appareillage théorique de la « sociologie des épreuves », les propos de GACEURS et de bénévoles/salariés du commerce équitable sont analysés afin de voir si le concept de Développement Durable porte en lui un projet sociétal, un référentiel fédérateur, apte à mobiliser des consom’acteurs autour de revendications partagées. L’analyse met en évidence un corpus critique commun articulé autour de quatre axes, dont trois relèvent bien du développement durable, mais nuance ses conclusions au vu de la faiblesse de la grammaire argumentative construite, et des contradictions qui la parcourent. [less ▲]

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See detailLa pratique des inventaires multi-ressources dans les forêts communautaires, ou comment rendre la foresterie communautaire inaccessible aux villageois
Meunier, Quentin; Vermeulen, Cédric ULg; Boldrini, Sylvie et al

E-print/Working paper (2013)

Des inventaires trop complexes imposés aux populations locales risquent de freiner considérablement l'appropriation des futures forêts communautaires gabonaises. La présente fiche technique compare les ... [more ▼]

Des inventaires trop complexes imposés aux populations locales risquent de freiner considérablement l'appropriation des futures forêts communautaires gabonaises. La présente fiche technique compare les avantages et inconvénients des inventaires par poches, des inventaires d'exploitation habituellement réalisés dans les Forêts Communautaires camerounaises et une approche plus simple par normes proposée par l'équipe rédactionnelle. [less ▲]

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See detailThe agyieus pillar, Egyptian legal papyri, and the cult of Arsinoe Philadephos in the streets of Alexandria
Caneva, Stefano ULg

E-print/Working paper (2013)

This paper is divided into two sections. The first aims to offer a thorough discussion of the agyieus and of types of altar for Arsinoe Philadelphos as well as of the offerings devoted to her in the ... [more ▼]

This paper is divided into two sections. The first aims to offer a thorough discussion of the agyieus and of types of altar for Arsinoe Philadelphos as well as of the offerings devoted to her in the Ptolemaic kingdom. The second explores the relationship that exists between the agyieus and the creation of cultic double names of Arsinoe in the streets of Alexandria. By combining the evidence on Arsinoe’s altars with a set of legal papyri attesting her divine names in Alexandria, I argue that in the Ptolemaic capital, the agyieis had a twofold function. They served firstly, as cult places for Arsinoe and secondly, as city landmarks. I will also argue that the second function of the agyieis, as city landmarks, survived the Ptolemaic cult of the Philadelphos and was ultimately preserved in long-lasting toponyms. [less ▲]

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See detailThe state against itself
Maiorano, Diego ULg

E-print/Working paper (2013)

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See detailAnalyse des divergences entre forêts communautaires et permis de gré à gré au Gabon
Meunier, Quentin; Moumbogou; Boldrini, Sylvie et al

E-print/Working paper (2013)

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See detailNew institutional economic theories of non-profits and cooperatives: a critique from an evolutionary perspective
Bauwens, Thomas ULg

E-print/Working paper (2013)

Traditional economic theories of social enterprises rely on new institutional economics. Although these theories have an undeniable explanatory power, they display a series of non-negligible flaws ... [more ▼]

Traditional economic theories of social enterprises rely on new institutional economics. Although these theories have an undeniable explanatory power, they display a series of non-negligible flaws. Evolutionary and complexity approaches in economics may help overcome these limits. The object of this article is, in a first time, to review the different new institutional theories applied to non-profits and cooperatives and, in a second time, to present some criticisms addressed to new institutional economics. We concentrate on two controversial aspects of the latter: on the one hand, its underlying hypotheses about individuals and, in particular, bounded rationality and opportunism; on the other hand, its neglect of the emergent and evolving nature of economic phenomena and of the importance of history and the environment in agents’ institutional choices. For each criticism, we make proposals, mainly inspired by evolutionary and complexity approaches in economics, in order to overcome these limits. [less ▲]

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See detailLes PME en croissance: leadership et management
Robert, Jocelyne ULg; Renerken, Alexandre

E-print/Working paper (2013)

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See detailGuide de lemmatisation des textes grecs: Théorie et pratique
Denizot, Camille ULg; Vandersmissen, Marc ULg

E-print/Working paper (2013)

Afin d’optimiser à la fois les procédures de lemmatisation du grec, mais aussi et surtout leur exploitation pour le chercheur, ce guide cherche à améliorer le système de rattachement au lemme et de ... [more ▼]

Afin d’optimiser à la fois les procédures de lemmatisation du grec, mais aussi et surtout leur exploitation pour le chercheur, ce guide cherche à améliorer le système de rattachement au lemme et de catégorisation des parties du discours pour qu’il soit à la fois souple et rigoureux. Il est donc question d’adapter les méthodes actuelles pour qu’elles permettent – tout en répondant à des exigences de faisabilité (technique et temporelle), de pertinence scientifique et de liberté d’analyse dans les cas d’ambiguïtés – une meilleure stabilité de traitement des données textuelles. [less ▲]

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See detailR&D, Capital Structure, and Agency Conflict: A Contingent Claim Analysis
Tiwari, Amaresh Kumar ULg

E-print/Working paper (2013)

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See detailExcess Return Forecast Using a Dynamic Asset Class Factor Model
Hübner, Georges ULg; Sougné, Danielle ULg; Wijnandts, Jean-Charles ULg

E-print/Working paper (2012)

We propose a Dynamic Hierarchical Factor Model using Asset classes to predict mutual funds excess returns. We use different forecast combination schemes of bivariate model considering each asset class ... [more ▼]

We propose a Dynamic Hierarchical Factor Model using Asset classes to predict mutual funds excess returns. We use different forecast combination schemes of bivariate model considering each asset class factor in isolation. Primary analysis highlights the importance to account for asset class specific variations together with between classes or common variations. Further refinements of the a priori repartition are however in order. Forecasting performance of the model outperforms the historical mean benchmark both in terms of MSPE and utility based criteria. A forecasting exercise matching more closely real-time conditions must be undertaken to validate these initial results. [less ▲]

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See detailLettre d'Information trimestrielle du projet N°8
Meunier, Quentin; Moumbogou; Vermeulen, Cédric ULg

E-print/Working paper (2012)

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See detailLes investisseurs institutionnels dans les Maisons de luxe familiales belges: entre diabolisation et sacralisation
Riguelle, France ULg; Van Caillie, Didier ULg

E-print/Working paper (2012)

Abstract : Belgian family luxury Houses are increasingly confrontated to a problem of independence caused by the growing influence of great financial groups and of private investment funds, on the one ... [more ▼]

Abstract : Belgian family luxury Houses are increasingly confrontated to a problem of independence caused by the growing influence of great financial groups and of private investment funds, on the one hand, and by a problem of image due to their Belgian origin, on the other hand. Nevertheless, their growing need for internationalization in order to counter the threats of the market and to seize opportunities leads them to concede one part of their control to institutional investors. The interest of this research is to study the potential impact, as perceived by the leaders of Belgian luxury Houses, of the venue of public institutional investors in their capital structure. We show that this perceived impact oscillates between sacralization and diabolisation of public institutional investors. [less ▲]

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See detailComparison Between Mornigstar Ratings And Traditional Performance Measures Ratings
Bodson, Laurent ULg; Delhalle, Stéphanie ULg; Sougné, Danielle ULg

E-print/Working paper (2012)

In this paper, we compare Morningstar ratings with those obtained using the same methodology of rating attribution with a set of commonly used performance measures. We look at three types of investment ... [more ▼]

In this paper, we compare Morningstar ratings with those obtained using the same methodology of rating attribution with a set of commonly used performance measures. We look at three types of investment horizons: 3-year, 5-year and 10-year ratings. Our analysis focuses on Open-End US Mutual Funds available in Morningstar Direct Database from which we create three sets of 16,617, 13,505 and 7,992 funds corresponding respectively to the three investment horizons analyzed. Our results show that Morningstar ratings are very close (correlation around 80%) to ratings obtained with Sharpe’s alpha, Jensen’s alpha, Four-factor alpha and Excess returns. And less significantly, we also observe that ratings given by the Sortino ratio, Sharpe MVaR, M-squared, Sharpe ratio, One-factor information ratio, Four-factor information ratio, Prospect ratio and Stutzer index are quite similar to Morningstar’s ratings (correlation lying between 70% and 78%). At the other end of the spectrum, however, ratings obtained with Annual return diverge widely from Morningstar ratings. We also analyse which explanatory variables can explain the differences between ratings computed with Morningstar as compared with the alternative performance measures using a probit regression. We find that Load adjustments, tax and risk included by Morningstar in the computation of MRAR are often determining. Expense ratio, Return Skewness and the three factors of the Fama-French model (Beta, Size load and Book-to-market loading) can be significant determinants depending on the performance measure analyzed and on the selected investment horizon. Fund characteristics such as Age, Fund size, Turnover rate and Manager tenure are not statistically significant in determining the differences in ratings. Besides, we analyze differences between ratings (in terms of number of STARs) and we confirm previous results (i.e. the link between Morningstar’s and the alternative performance measures, but also the explanatory capacity of the load for lots of differences between ratings). Finally, we test all possible combinations of our set of performance measures, and observe that Sharpe’s alpha, excess return, Sharpe MVaR, Four-factor alpha and Jensen’s alpha are part of the best combinations. As a conclusion, Morningstar ratings can be replicated using simple and traditional performance measures but the replication is less accurate when tax and loads features are important. Therefore, Morningstar data management and access bring the most of its ratings’ value added. [less ▲]

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See detailCoûts d’efficience des dépositaires centraux des titres des pays africains
Teuwa Nkeuwo, Mathieu Hugues ULg; Muller, Aline ULg

E-print/Working paper (2012)

This paper examines the potential of economies of scale and scope among the African central securities depository institutions. We address whether the consolidation of settlement and custody activities of ... [more ▼]

This paper examines the potential of economies of scale and scope among the African central securities depository institutions. We address whether the consolidation of settlement and custody activities of securities make these institutions efficient in light of the costs of service parameter. To do this, we rely on the translog cost function [introduced by Christensen et al. (1971)] and the constant elasticity of substitution of seven central securities depositories in Africa over the period 2004-2009. The results show the existence of significant economies of scale and scope in these institutions. The extent of these economies differs upon the size of the institution and the level of automation mechanisms to combine securities settlement and custody activities. Our findings also indicate that, unlike large institutions in countries such as South Africa and Mauritius, which have heavily invested in automation mechanisms, smaller institutions have higher service costs, which implies a need for consolidation of activities to reduce these costs. [less ▲]

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See detailPlan Simple de Gestion à vocation de production de bois énergie
Dubiez, Emilien; Vermeulen, Cédric ULg; Larzilière, Adélaïde

E-print/Working paper (2012)

Les zones d’interventions du Projet Makala présentent des contextes différents liés à l’occupation spatiale coutumière, l’organisation des structures sociales traditionnelles (lignage, clan, chefferie ... [more ▼]

Les zones d’interventions du Projet Makala présentent des contextes différents liés à l’occupation spatiale coutumière, l’organisation des structures sociales traditionnelles (lignage, clan, chefferie coutumière), les types de formations végétales présentes dans la zone et les activités principales des populations. L’ensemble de ces éléments structure l’intervention du projet dans son objectif d’aménagement des espaces forestiers périurbains dégradés. Des enquêtes d’identification du finage et des terroirs villageois partenaires ont d’abord été réalisées pour caractériser le contexte social et environnemental d’intervention. Les données recueillies ont constituées la base de travail de la construction du processus d’élaboration des Plans Simples de Gestion (PSG). Le présent document présente les étapes structurant le PSG, l’outil de démarche participatif permettant une appropriation collective du processus et les activités techniques développées pour la reconstitution des espaces forestiers dégradés. [less ▲]

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