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See detailBack to materialism Reflections on Marx’s labour, praxis, cooperative and libertarian socialism in the 19th century
Frère, Bruno ULg

E-print/Working paper (2017)

From Marx to Althusser, the materialist approach has tended to assume that individuals (that is, workers, proletarians and other social actors), unconsciously reproduce the social structures of capitalism ... [more ▼]

From Marx to Althusser, the materialist approach has tended to assume that individuals (that is, workers, proletarians and other social actors), unconsciously reproduce the social structures of capitalism which alienate them. It is assumed that individuals accept the conditions forced upon them and no longer seek to rebel against a world which substantially impoverishes their labour, their spirit and their creativity. In this paper, I will try to show that by dint of favouring almost exclusively Marx's concept of alienation, there is a considerable risk that materialist thought will adopt only a negative path. Whilst I acknowledge Marx’s significance to materialism, I wish to argue that his stance should be combined with that of the anarchist and libertarian French thinker Proudhon. Proudhon has succeeded in presenting a conception of the worker as more than just alienated. Workers can also cooperate and experience a reciprocity seemingly at odds with the character of capitalism. Under Proudhon’s influence materialism takes a positive turn, enabling us to avoid falling into the utopianism that the theory of social economy employs to critique capitalism – a utopianism that renders its critique even less effective than that of Marx. [less ▲]

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See detailHow to account for new forms of resistance to domination: An argument for a materialist renewal in European social theory
Frère, Bruno ULg; Tulle, Emmanuelle

E-print/Working paper (2017)

Many significant intellectual developments have taken place in 20th century European social theories. Notably the first Frankfurt School and Bourdieu’s work have successfully shown how workers, social ... [more ▼]

Many significant intellectual developments have taken place in 20th century European social theories. Notably the first Frankfurt School and Bourdieu’s work have successfully shown how workers, social actors, etc. are alienated or dominated by capitalist social structures. But according to Habermas, neither perspective successfully allows for the possibility that people could contribute to their own emancipation. The emergence of new forms of social resistance to domination such as those embodied by the Indignados, Anonymous, Femen, the practitioners of alternative economy, movements of unemployed people or illegals compels us to envisage the possibility for emancipation, but how? In this paper we explore opportunities for accounting for this by considering the work of a range of other European social theorists, more specifically Boltanski whose critical intent is embodied in his pragmatic sociology, and evident in his coining and use of the concept of the world. In addition we will consider Latour’s own pragmatic stance as we believe that despite his disinterest in new social movements, his work, informed by pure immanence, might offer potential solutions. But we would argue that even in these innovations there is either a persistent tendency to imagine emancipation primarily as a return to some ideal state or a lack of critical engagement with alienation. In response, we propose a materialist renewal, which will lead us to ponder on the political role of sociologists. [less ▲]

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See detailThe np- Control Charts with the Guaranteed In-Control Performance
Faraz, Alireza ULg; Heuchenne, Cédric ULg

E-print/Working paper (2016)

In this paper, we evaluate the in-control performance of np-control charts with estimated parameters. We then apply the bootstrap method to adjust the control charts’ limits to guarantee the desired in ... [more ▼]

In this paper, we evaluate the in-control performance of np-control charts with estimated parameters. We then apply the bootstrap method to adjust the control charts’ limits to guarantee the desired in-control average run length (ARL0) value in monitoring stage. The adjusted limits ensure that ARL0 would take a value greater than the desired value (say, B) with a certain specified probability, that is Pr⁡(ARL_0>B)=1-ρ. We finally provide users with tables which with practitioners do not need to do bootstrapping Phase I data set to obtain the control limit thresholds. [less ▲]

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See detailA Comparison of Departure Time of Day Formulations
Lurkin, Virginie ULg; Garrow, Laurie; Higgins, Matthew et al

E-print/Working paper (2016)

Airline passengers’ itinerary choices are influenced by many factors including carriers, prices, the number of connections, and departure times. This paper compares three different methods that have been ... [more ▼]

Airline passengers’ itinerary choices are influenced by many factors including carriers, prices, the number of connections, and departure times. This paper compares three different methods that have been used to model departure time of day preferences. The first is a discrete formulation that uses indicator variables to represent the hour of departure. The next two methods are based on a continuous formulation that uses a series of sine and cosine functions. One assumes departure time preferences over a 24-hour cycle and the other uses shorter cycle lengths that account for fewer departures during certain hours of the day. We compare models using itineraries in the Continental U.S. that are separated by two time zones. Although the discrete formulation fits the data better, the two continuous time of day formulations are preferred as they provide more intuitive predictions and require fewer parameters. Results between the two continuous time of day formulations are similar but differ in how strongly they weight itineraries that depart very early or very late in the day. Based on empirical results, we recommend testing both 24-hour and less than 24-hour cycle lengths for a particular dataset. [less ▲]

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See detailAccounting for Price Endogeneity in Airline Itinerary Choice Models: An Application to Continental U.S. Markets
Lurkin, Virginie ULg; Garrow, Laurie; Higgins, Matthew et al

E-print/Working paper (2016)

Network planning models, which forecast the profitability of airline schedules, support many critical decisions, including equipment purchase decisions. Network planning models include an itinerary choice ... [more ▼]

Network planning models, which forecast the profitability of airline schedules, support many critical decisions, including equipment purchase decisions. Network planning models include an itinerary choice model which is used to allocate air total demand in a city pair to different itineraries. Multinomial logit (MNL) models are commonly used in practice and capture how individuals make trade-offs among different itinerary attributes; however, none that we are aware of account for price endogeneity. This study formulates an itinerary choice model that is consistent with those used by industry and corrects for price endogeneity using a control function that uses several types of instrumental variables. We estimate our models using database of more than 3 million tickets provided by the Airlines Reporting Corporation. Results based on Continental U.S. markets for May 2013 departures show that models that fail to account for price endogeneity overestimate customers’ value of time and result in biased price estimates and incorrect pricing recommendations. The size and comprehensiveness of our database allows us to estimate highly refined departure time of day preference curves that account for distance, direction of travel, the number of time zones traversed, departure day of week and itinerary type (outbound, inbound or one-way). These time of day preference curves can be used by airlines, researchers, and government organizations in the evaluation of different policies such as congestion pricing. [less ▲]

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See detailComparison of local outliers detection techniques in spatial multivariate data
Ernst, Marie ULg; Haesbroeck, Gentiane ULg

E-print/Working paper (2016)

Outlier detection techniques in spatial data should allow to identify two types of outliers: global and local ones. Local outliers typically have non-spatial attributes that strongly differ from those ... [more ▼]

Outlier detection techniques in spatial data should allow to identify two types of outliers: global and local ones. Local outliers typically have non-spatial attributes that strongly differ from those observed on their neighbors. Detecting local outliers requires to be able to work locally, on neighborhoods, in order to take into account the spatial dependence between the statistical units under consideration, even though the outlyingness is usually measured on the non-spatial variables. Many procedures have been outlined in the literature, but their number reduces when one wants to deal with multivariate non-spatial attributes. In this paper, focus is on the multivariate context. A review of existing procedures is done. A new approach, based on a two-step improvement of an existing one, is also designed and compared with the benchmarked methods by means of examples and simulations. [less ▲]

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See detailStructure et négativité dans la Préface de 1961 à L'Histoire de la folie
Oulc'hen, Hervé ULg

E-print/Working paper (2016)

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See detailGeneralized Pascal triangle for binomial coefficients of words
Leroy, Julien ULg; Rigo, Michel ULg; Stipulanti, Manon ULg

E-print/Working paper (2016)

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See detailOnline Learning for Strong Branching Approximation in Branch-and-Bound
Marcos Alvarez, Alejandro ULg; Wehenkel, Louis ULg; Louveaux, Quentin ULg

E-print/Working paper (2016)

We present an online learning approach to variable branching in branch-and-bound for mixed-integer linear problems. Our approach consists in learning strong branching scores in an online fashion and in ... [more ▼]

We present an online learning approach to variable branching in branch-and-bound for mixed-integer linear problems. Our approach consists in learning strong branching scores in an online fashion and in using them to take branching decisions. More specifically, numerical scores are used to rank the branching candidates. If, for a given variable, the learned approximation is deemed reliable, then the score for that variable is computed thanks to the learned function. If the approximation is not reliable yet, the real strong branching score is used instead. The scores that are computed through the real strong branching procedure are fed to the online learning algorithm in order to improve the approximated function. The experiments show promising results. [less ▲]

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See detailPermutations and negative beta-shifts
Charlier, Emilie ULg; Steiner, Wolfgang

E-print/Working paper (2016)

Elizalde (2011) characterized which permutations can be obtained by ordering consecutive elements in the trajectories of (positive) beta-transformations and beta-shifts. We prove similar results for ... [more ▼]

Elizalde (2011) characterized which permutations can be obtained by ordering consecutive elements in the trajectories of (positive) beta-transformations and beta-shifts. We prove similar results for negative bases beta. [less ▲]

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See detailOn the processing of red pigment by late mousterian Neanderthals in Ormesson, Seine-et-Marne, France, 47000 years ago
Salomon, Hélène ULg; Bodu, Pierre; Geurten, Stéphanie et al

E-print/Working paper (2016)

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See detailWhy Did the Industrial Revolution Start in Britain?
Van Neuss, Leif ULg

E-print/Working paper (2015)

The main goal of this paper is to provide an integrated overview of the literature devoted to identifying the causes of the British industrial revolution. Why did the industrial revolution, a fascinating ... [more ▼]

The main goal of this paper is to provide an integrated overview of the literature devoted to identifying the causes of the British industrial revolution. Why did the industrial revolution, a fascinating and multifaceted event which brought about modern economic growth, occur in eighteenth-century Britain? This question has animated a lot of discussions among scholars and is still nowadays heatedly debated in the literature. This debate is reflected in the large spectrum of theories which aim at explaining the true origins of the British industrialization. The paper first sheds light on a rising debate concerning the evolution of British incomes per capita before the British industrial revolution and the “Great Divergence”. The paper then investigates the proposed causes of the British industrialization, aggregating them into seven broad categories, i.e. (1) geography and natural resources, (2) demography, (3) agricultural progress, (4) demand-side factors, (5) trade and empire, (6) institutional and political factors, (7) science, technology, and human capital. [less ▲]

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See detailLarge neighborhood search for multi-trip vehicle routing
François, Véronique ULg; Arda, Yasemin ULg; Crama, Yves ULg et al

E-print/Working paper (2015)

We consider two large neighborhood search approaches for the multi-trip vehicle routing problem, where each vehicle can perform several routes during the working shift to serve a set of customers. The ... [more ▼]

We consider two large neighborhood search approaches for the multi-trip vehicle routing problem, where each vehicle can perform several routes during the working shift to serve a set of customers. The problem specifically arises when customers are close to each other and/or when the demands are large. A common approach in the literature consists in solving this problem by mixing vehicle routing heuristics with bin packing routines to assign routes to vehicles. We compare this approach with the use of specific operators designed to tackle the routing and the assignment aspects of the problem simultaneously. We provide several best known solutions for benchmark instances. At the end of the work, we give insights about the proposed algorithm configurations by analyzing the behavior of several method components. [less ▲]

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See detail25 novembre 2015 : cent ans de Relativité
De Rop, Yves ULg

E-print/Working paper (2015)

La théorie proposée par Einstein au début du XXe siècle porte bien mal son nom; car si, historiquement, l'accent fut mis d'abord sur la relativité de certaines notions (en particulier, la mesure de l ... [more ▼]

La théorie proposée par Einstein au début du XXe siècle porte bien mal son nom; car si, historiquement, l'accent fut mis d'abord sur la relativité de certaines notions (en particulier, la mesure de l'intervalle de temps écoulé entre deux événements donnés), on a compris par la suite qu'elle reposait plus fondamentalement sur l'existence de quantités absolues, c'est-à-dire, dont la mesure est identique pour tous les observateurs, quel que soit leur état de repos ou de mouvement. Ces quantités sont inconnues de la mécanique de Newton, laquelle ne reconnaît qu'un seul invariant : le temps. Ce texte cherche à retracer, avec un minimum de formalisme, comment s'est imposé un nouveau cadre géométrique pour la physique, dominé par cette exigence d'invariance des mesures spatio-temporelles et intégrant une description révolutionnaire de la gravitation. [less ▲]

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See detailMulti-period vehicle allocation with uncertain transportation requests
Crama, Yves ULg; Pironet, Thierry ULg

E-print/Working paper (2015)

This work investigates optimization techniques for a multi-period vehicle allocation problem with uncertain requests. A company owning a limited fleet of trucks attempts to maximize its operational profit ... [more ▼]

This work investigates optimization techniques for a multi-period vehicle allocation problem with uncertain requests. A company owning a limited fleet of trucks attempts to maximize its operational profit over an infinite horizon by optimally assigning transportation orders to the vehicles. Its profit stems from profits collected when transporting full truckloads, minus costs incurred when waiting or when moving unladen. The stochastic component of the problem arises from the uncertainty on the realization of each transportation order. The methodology is based on optimizing decisions for deterministic scenarios. Several policies are generated in this way, either by simple heuristics, or by more complex approaches, such as consensus and restricted expectation algorithms, or from network flow formulations over subtrees of scenarios. Myopic and a-posteriori deterministic optimization models are used to compute bounds allowing for performance evaluation. Numerical experiments are performed on various instances featuring different numbers of orders, graph sizes, sparsity, and probability distributions, and the performance of the algorithms is assessed by statistical tests. The robustness of various policies with respect to erroneous evaluations of the probability distributions is also analyzed. [less ▲]

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See detailL’accompagnement de projets d’entrepreneuriat social dans leurs phases initiales
Dufays, Frédéric ULg; Lovens, Caroline ULg; Mertens de Wilmars, Sybille ULg

E-print/Working paper (2015)

L’entrepreneuriat social connaît depuis quelques années un intérêt croissant. Mais pour les entrepreneurs sociaux, concilier les dimensions sociales et économiques demande de faire face à des défis bien ... [more ▼]

L’entrepreneuriat social connaît depuis quelques années un intérêt croissant. Mais pour les entrepreneurs sociaux, concilier les dimensions sociales et économiques demande de faire face à des défis bien spécifiques. Ne faut-il donc pas favoriser un accompagnement sur-mesure et modulable ? C’est le défi qu’a choisi de relever en Belgique francophone le programme ImpulCera en proposant aux entrepreneurs sociaux un soutien financier pour la réalisation d’une étude de faisabilité et pour le lancement de leur projet. Le présent article présente quelques résultats de l’évaluation de ce programme ainsi que les enseignements qui peuvent en être dégagés. [less ▲]

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

E-print/Working paper (2015)

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 detailMarkets flash graphs
Choffray, Jean-Marie ULg

E-print/Working paper (2015)

A graph is worth a hundred words... A good graph may suggest some new heuristics. And…, a series of excellent graphs may provide the backbone of a theory! The goal of this paper is to share a set of ... [more ▼]

A graph is worth a hundred words... A good graph may suggest some new heuristics. And…, a series of excellent graphs may provide the backbone of a theory! The goal of this paper is to share a set of graphs from multiple sources that offer as many flashes on current and past market conditions. Inevitably, these graphs reflect my own biases and questionings. They are not meant to induce any action aside, maybe, from their integration in a personal Information System. The Great Recession of 2008, whose consequences are still unfolding, has been for each of us a powerful invitation to modesty. We live in a world where improbable, unthinkable and impossible events happen every day... More than ever, it’s time to sit down, shut up, watch out, build graphs, and think… hard! [less ▲]

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See detailBenchmarking for Bayesian Reinforcement Learning
Castronovo, Michaël ULg; Ernst, Damien ULg; Couëtoux, Adrien ULg et al

E-print/Working paper (2015)

In the Bayesian Reinforcement Learning (BRL) setting, agents try to maximise the col- lected rewards while interacting with their environment while using some prior knowledge that is accessed beforehand ... [more ▼]

In the Bayesian Reinforcement Learning (BRL) setting, agents try to maximise the col- lected rewards while interacting with their environment while using some prior knowledge that is accessed beforehand. Many BRL algorithms have already been proposed, but even though a few toy examples exist in the literature, there are still no extensive or rigorous benchmarks to compare them. The paper addresses this problem, and provides a new BRL comparison methodology along with the corresponding open source library. In this methodology, a comparison criterion that measures the performance of algorithms on large sets of Markov Decision Processes (MDPs) drawn from some probability distributions is defined. In order to enable the comparison of non-anytime algorithms, our methodology also includes a detailed analysis of the computation time requirement of each algorithm. Our library is released with all source code and documentation: it includes three test prob- lems, each of which has two different prior distributions, and seven state-of-the-art RL algorithms. Finally, our library is illustrated by comparing all the available algorithms and the results are discussed. [less ▲]

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See detailBlues et Wallon - Elmore D, l'intégrale cåzî complète en cinq CDs
Sacré, Robert ULg

E-print/Working paper (2015)

Analyse d'une anthologie de 5 Cds représentant l'intégrale" cåzî "complète des enregsitrements d'Elmore D ( Prof. Daniel Droixhe) pour la compagnie française FREMEAUX et ASS.

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See detailDans le dédale des Musiques Africaines-Américaines
Sacré, Robert ULg

E-print/Working paper (2015)

Notes du cours " Histoire des Musiques Africaines Américaines, des origines à nos jours" (remise à jour 2015) - cours dispensé depuis 1984

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See detailQuadratic reformulations of nonlinear binary optimization problems
Anthony, Martin; Boros, Endre; Crama, Yves ULg et al

E-print/Working paper (2015)

Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these ... [more ▼]

Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these problems when the objective function is a quadratic polynomial. However, no similarly efficient methods are available for the higher degree case. Since high degree objectives are becoming increasingly important in certain application areas, such as computer vision, various techniques have been recently developed to reduce the general case to the quadratic one, at the cost of increasing the number of variables. In this paper we initiate a systematic study of these quadratization approaches. We provide tight lower and upper bounds on the number of auxiliary variables needed in the worst-case for general objective functions, for bounded-degree functions, and for a restricted class of quadratizations. Our upper bounds are constructive, thus yielding new quadratization procedures. Finally, we completely characterize all ``minimal'' quadratizations of negative monomials. [less ▲]

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See detailDoes formal child care availability for 0-3 year olds boost mothers' employment rate? Panel data based evidence from Belgium
Dujardin, Claire; Fonder, Muriel; Lejeune, Bernard ULg

E-print/Working paper (2015)

In 2003, a new multi-annual program aimed at increasing the availability of formal child care for 0-3 year old children was launched in Wallonia, the French-speaking part of Belgium. This paper is ... [more ▼]

In 2003, a new multi-annual program aimed at increasing the availability of formal child care for 0-3 year old children was launched in Wallonia, the French-speaking part of Belgium. This paper is interested in evaluating if this increased availability of formal child care resulted in a higher employment rate for women with at least one child under 3. To this end, we use a difference-in-differences approach based on municipality-level panel data, taking advantage of the fact that the increase in availability of formal child care differed greatly across municipalities. We find that the raise in child care availability significantly increased the maternal employment rate, but to a lesser extent than expected, most likely because of a substantial crowding-out effect. [less ▲]

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See detailGarantir la légalité et assurer la traçabilité. Deux piliers de la mise en oeuvre de l'APV-FLEGT.
Moumbogou, Carl; Meunier, Quentin; Bracke, Charles et al

E-print/Working paper (2015)

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See detailLes forêts communautaires et l'APV-FLEGT au Gabon
Moumbogou, Carl; Meunier, Quentin; Mvou Biyogo, T. et al

E-print/Working paper (2015)

Promu par l’Union européenne depuis 2003, le plan d’action FLEGT propose une approche novatrice de lutte contre l’exploitation illégale des forêts, en établissant un lien entre l’amélioration de la ... [more ▼]

Promu par l’Union européenne depuis 2003, le plan d’action FLEGT propose une approche novatrice de lutte contre l’exploitation illégale des forêts, en établissant un lien entre l’amélioration de la gouvernance dans les pays producteurs et l’accès au marché de l’UE. Ce plan concerne tous les titres forestiers, dont les forêts communautaires. Ces dernières ont été désignées au Gabon comme source légale de bois à la faveur des négociations d’un APVFLEGT avec l’UE. Dès lors, et afin de stabiliser le système qui sera mis en place, il est nécessaire de préparer des outils adaptés permettant d’articuler le FLEGT et les forêts communautaires. [less ▲]

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See detailBayesian inference in an extended SEIR model with nonparametric disease transmission rate: an application to the Ebola epidemic in Sierra Leone
Frasso, Gianluca ULg; Lambert, Philippe ULg

E-print/Working paper (2015)

The 2014 Ebola outbreak in Sierra Leone is analyzed using an extension of the SEIR compartmental model. The unknown parameters of the system of differential equations are estimated by combining data on ... [more ▼]

The 2014 Ebola outbreak in Sierra Leone is analyzed using an extension of the SEIR compartmental model. The unknown parameters of the system of differential equations are estimated by combining data on the number of new (laboratory confirmed) Ebola cases reported by the Ministry of Health and prior distributions for the transition rates elicited using information collected by the WHO Response Team (2014) during the follow-up of specific Ebola cases. The evolution over time of the disease transmission rate is modeled nonparametrically using penalized B-splines. Our framework represents a valuable and robust stochastic tool for the study of an epidemic dynamic from irregular and possibly aggregated case data. Simulations and the analysis of the 2014 Sierra Leone Ebola data highlight the merits of the proposed methodology. [less ▲]

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See detailOptimal Enforcement of Competition Policy: The Commitments Procedure under Uncertainty
Gautier, Axel ULg; Petit, Nicolas ULg

E-print/Working paper (2015)

Since the introduction of a commitments procedure in EU antitrust policy (Article 9 of Council Regulation 1/2003), the European Commission has extensively settled cases of alleged anticompetitive ... [more ▼]

Since the introduction of a commitments procedure in EU antitrust policy (Article 9 of Council Regulation 1/2003), the European Commission has extensively settled cases of alleged anticompetitive practices. In this paper, we use a formal model of law enforcement (Bebchuk, 1984; Shavell, 1988) to identify the optimal procedure to resolve cases in a context of uncertainty related to the law (L-uncertainty) and to the facts (F-uncertainty). We show that commitments are suboptimal when L-uncertainty is high. Furthermore, the generalized use of commitments creates an additional risk of under-enforcement when F-uncertainty is significant. [less ▲]

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See detailParty autonomy in international family relationships : a research agenda
Wautelet, Patrick ULg

E-print/Working paper (2015)

In recent years, party autonomy has conquered new grounds in cross-border private relationships. Building on first attempts in national codifications, party autonomy has become one of the leading ... [more ▼]

In recent years, party autonomy has conquered new grounds in cross-border private relationships. Building on first attempts in national codifications, party autonomy has become one of the leading principles used in various EU regulations dealing with cross-border family relationships. It can now be found in successions, in divorce, in maintenance matters. This new trend has been greeted sometimes with enthusiasm, sometimes with skepticism. While these Regulations constrain the choice that parties can make, it cannot be denied that the principle of freedom of choice has been openly embraced by the European legislator. Hence this principle evolved, at least within the EU, from what was until recently a marginal phenomenon to a well-respected solution for cross-border family relationships This (r-)evolution occurred quite fast and has attracted much attention. However, much of the research in this area has adopted a limited perspective, focusing exclusively on the possibilities and limits of choice in one specific instrument or adopting a comprehensive outlook but with a strong positive flavor. While it is true that a number of contributions provide excellent food for thought, the overall impression is that more time and more research is needed to start apprehending the fundamental questions raised by this evolution. At this stage, it may be too early to offer a comprehensive study of all questions raised by party autonomy in private international law. New developments may in fact modify the picture soon and add to the fields conquered by party autonomy. At the same time, the relative novelty of the changes makes it difficult to take full stock of all issues raised by the development of party autonomy. This is why scholars should first attempt to define a research agenda. This paper offers a first scratch by exploring various questions which should figure prominently in such agenda. It is by no means meant to be exhaustive. Rather, an attempt will be made to shed some light on the main questions raised by recent evolution in the hope of being an invitation for further research. [less ▲]

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See detailApproche agroforestière. Synthèse des travaux menés par le projet DACEFI2 en agroforesterie. Document de capitalisation.
Boldrini, Sylvie; Meunier, Quentin; Boukouendji, Basile et al

E-print/Working paper (2015)

Le projet DACEFI-2 a eu pour mission première la promotion de la foresterie communautaire comme outil de développement des communautés rurales. L’approche au Gabon en matière de gestion des terroirs ... [more ▼]

Le projet DACEFI-2 a eu pour mission première la promotion de la foresterie communautaire comme outil de développement des communautés rurales. L’approche au Gabon en matière de gestion des terroirs villageois s’est voulue plus embrassante, promouvant en sus de l’exploitation forestière des activités comme l’agriculture, le maraîchage, la collecte des produits forestiers non ligneux ou encore l’agroforesterie. L’agroforesterie est une thématique qui converge parfaitement avec la gestion raisonnée de la forêt, et idéalement avec les modes d’interaction préexistants des villageois avec celle-ci. Concilier dans un même espace la culture de plantes vivrières et l’accès à des arbres à fort intérêt socio-économique apporte une plus-value notoire aux parcelles cultivées. L’optimisation des techniques culturales permet une meilleure productivité et une incitation à la sédentarisation des cultures, élément important à considérer compte tenu des difficultés d’entretien des parcelles éloignées du village (notamment liées aux dégâts causés par les animaux). Ce recueil compile les travaux réalisés en agroforesterie par les équipes du projet DACEFI-2. Il rappelle la stratégie d’intervention et les différentes activités menées, de la sensibilisation auprès des plus jeunes à la promotion de certains produits forestiers non ligneux à potentiel économique avéré. La promotion de l’arbre, de la récolte de la graine jusqu’à sa plantation en passant par sa mise en pépinière aura également animé toute l’équipe durant ces années d’exercice, afin de faire un peu plus valoir ses multiples intérêts et susciter les efforts de gestion, de conservation et de reboisement. [less ▲]

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See detailImportance et rôle de l’investissement…
Choffray, Jean-Marie ULg

E-print/Working paper (2015)

Quelques observations et réflexions en réponse à une question qui m’est souvent posée sur l’importance et le rôle des investisseurs. Ces « Charognards », particulièrement visés au cours des périodes de ... [more ▼]

Quelques observations et réflexions en réponse à une question qui m’est souvent posée sur l’importance et le rôle des investisseurs. Ces « Charognards », particulièrement visés au cours des périodes de tension géopolitique, de populisme ou de débauche monétaire, semblables à celle que nous vivons aujourd’hui. Ma réponse en peu de mots : les investisseurs sont des défenseurs de la valeur du travail par temps calme et des vigies dans la tempête ! [less ▲]

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See detailEntretien avec Kathryn Batchelor
Oumarou Mal Mazou, Rachid ULg

E-print/Working paper (2015)

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See detailPropriété coopérative et acceptabilité sociale de l’éolien terrestre
Bauwens, Thomas ULg

E-print/Working paper (2015)

Onshore wind power development in Belgium has provoked considerable opposition at the local level. To cope with this issue, wind power cooperatives seem to present important assets. This article explores ... [more ▼]

Onshore wind power development in Belgium has provoked considerable opposition at the local level. To cope with this issue, wind power cooperatives seem to present important assets. This article explores the reasons why these organizations are likely to enhance social acceptability of this technology. Then it confronts these normative assumptions with empirical data. The results of this analysis confirm the positive effect of cooperative ownership on the social acceptability of onshore wind turbines. [less ▲]

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See detailA semiparametric model for Generalized Pareto regression based on a dimension reduction assumption
Hambuckers, julien ULg; Heuchenne, Cédric ULg; Lopez, Olivier

E-print/Working paper (2015)

In this paper, we consider a regression model in which the tail of the conditional distribution of the response can be approximated by a Generalized Pareto distribution. Our model is based on a ... [more ▼]

In this paper, we consider a regression model in which the tail of the conditional distribution of the response can be approximated by a Generalized Pareto distribution. Our model is based on a semiparametric single-index assumption on the conditional tail index; while no further assumption on the conditional scale parameter is made. The underlying dimension reduction assumption allows the procedure to be of prime interest in the case where the dimension of the covariates is high, in which case the purely nonparametric techniques fail while the purely parametric ones are too rough to correctly fit to the data. We derive asymptotic normality of the estimators that we define, and propose an iterative algorithm in order to perform their practical implementation. Our results are supported by some simulations and a practical application on a public database of operational losses. [less ▲]

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See detailMachine Learning to Balance the Load in Parallel Branch-and-Bound
Marcos Alvarez, Alejandro ULg; Wehenkel, Louis ULg; Louveaux, Quentin ULg

E-print/Working paper (2015)

We describe in this paper a new approach to parallelize branch-and-bound on a certain number of processors. We propose to split the optimization of the original problem into the optimization of several ... [more ▼]

We describe in this paper a new approach to parallelize branch-and-bound on a certain number of processors. We propose to split the optimization of the original problem into the optimization of several subproblems that can be optimized separately with the goal that the amount of work that each processor carries out is balanced between the processors, while achieving interesting speedups. The main innovation of our approach consists in the use of machine learning to create a function able to estimate the difficulty (number of nodes) of a subproblem of the original problem. We also present a set of features that we developed in order to characterize the encountered subproblems. These features are used as input of the function learned with machine learning in order to estimate the difficulty of a subproblem. The estimates of the numbers of nodes are then used to decide how to partition the original optimization tree into a given number of subproblems, and to decide how to distribute them among the available processors. The experiments that we carry out show that our approach succeeds in balancing the amount of work between the processors, and that interesting speedups can be achieved with little effort. [less ▲]

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See detailThe role of market-oriented institutions in the deployment of renewable energies: evidences from Europe
Jacqmin, Julien ULg

E-print/Working paper (2015)

This paper investigates the link between economic freedom and the production of energy using renewable sources, with a specific focus on European countries. Using a dynamic panel approach, we find that ... [more ▼]

This paper investigates the link between economic freedom and the production of energy using renewable sources, with a specific focus on European countries. Using a dynamic panel approach, we find that this relationship is positive and significant. The results of our instrumental variable approach indicate further the causal channel between economic freedom and the deployment of renewable energies. Looking at the subcomponents of the economic freedom index, we find that long term price stability and freedom to trade boost the production of renewable energies. However, the importance given to markets, rather than governments, in the economy has no significant impact. [less ▲]

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See detailQue veut dire FLEGT ? Et pourquoi au Gabon ?
Moumbogou, Carl; Meunier, Quentin; Mvou Biyogo, T. et al

E-print/Working paper (2015)

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See detailA branch-and-price algorithm for 2-period vehicle routing problems
Crama, Yves ULg; Rezaei Sadrabadi, Mahmood ULg; Van Woensel, Tom

E-print/Working paper (2015)

We consider a Vehicle Routing Problem (VRP) with deterministic orders in two periods from a set of stores. Orders in period 1 (2) can be postponed (advanced) to the other period but any diversion from the ... [more ▼]

We consider a Vehicle Routing Problem (VRP) with deterministic orders in two periods from a set of stores. Orders in period 1 (2) can be postponed (advanced) to the other period but any diversion from the initial orders incurs a penalty. From the perspective of a Logistics Service Provider (LSP), such diversions could be beneficial if savings in the routing costs outweigh the penalties. So could they be from a store's view, as the store can set a high enough penalty to compensate the diversion from its own optimal orders. In this paper, we introduce a new model where we seek a better solution for the LSP, compared to solving two independent VRPs with fixed orders, by allowing orders to be fully postponed or advanced. We apply a branch-and-price algorithm to solve this model to optimality. Many cutting-edge techniques are implemented to have an efficient branch-and-price algorithm, and two ideas to possibly improve the upper bound are tested. We draw algorithmic and managerial insights based on our test instances. [less ▲]

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See detailInvesting in the Future
Pahud de Mortanges, Charles ULg

E-print/Working paper (2015)

This paper attempts to address the challenges of how to invest in Synthetic Biology firms, most of which are relatively new start-ups and unprofitable. Valuing an early-stage firm with only a brief ... [more ▼]

This paper attempts to address the challenges of how to invest in Synthetic Biology firms, most of which are relatively new start-ups and unprofitable. Valuing an early-stage firm with only a brief operating history, little or no operating profit (or even revenue), and an immature and untested business model, could be a formidable challenge. We propose a limited number of quantitative, and a larger number of qualitative criteria. An investor may consider these when faced with analyzing a new untried business, but one he/she believes has considerable potential for success in the future. [less ▲]

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Peer Reviewed
See detailOn the nature of cosmological time
Magain, Pierre ULg; Hauret, Clémentine ULg

E-print/Working paper (2015)

Time is a parameter playing a central role in our most fundamental modeling of natural laws. Relativity theory shows that the comparison of times measured by different clocks depends on their relative ... [more ▼]

Time is a parameter playing a central role in our most fundamental modeling of natural laws. Relativity theory shows that the comparison of times measured by different clocks depends on their relative motions and on the strength of the gravitational field in which they are embedded. In standard cosmology, the time parameter is the one measured by fundamental clocks, i.e. clocks at rest with respect to the expanding space. This proper time is assumed to flow at a constant rate throughout the whole history of the Universe. We make the alternative hypothesis that the rate at which cosmological time flows depends on the dynamical state of the Universe. In thermodynamics, the arrow of time is strongly related to the second law, which states that the entropy of an isolated system will always increase with time or, at best, stay constant. Hence, we assume that time measured by fundamental clocks is proportional to the entropy of the region of the Universe that is causally connected to them. Under that simple assumption, we build a cosmological model that explains the Type Ia Supernovae data (the best cosmological standard candles) without the need for exotic dark matter nor dark energy. [less ▲]

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See detailSequential testing of k-out-of-n systems with imperfect tests
Wenchao, Wei; Coolen, Kris ULg; Talla Nobibon, Fabrice et al

E-print/Working paper (2015)

A k-out-of-n system configuration requires that, for the overall system to be functional, at least k out of the total of n components be working. We consider the problem of sequentially testing the ... [more ▼]

A k-out-of-n system configuration requires that, for the overall system to be functional, at least k out of the total of n components be working. We consider the problem of sequentially testing the components of a k-out-of-n system in order to learn the state of the system, when the tests are costly and when the individual component tests are imperfect, which means that a test can identify a component as working when in reality it is down, and vice versa. Each component is tested at most once. Since tests are imperfect, even when all components are tested the state of the system is not necessarily known with certainty, and so reaching a lower bound on the probability of correctness of the system state is used as a stopping criterion for the inspection. We define different classes of inspection policies and we examine global optimality of each of the classes. We find that a globally optimal policy for diagnosing k-out-of-n systems with imperfect tests can be found in polynomial time when the predictive error probabilities are the same for all the components. Of the three policy classes studied, the dominant policies always contain a global optimum, while elementary policies are compact in representation. The newly introduced class of so-called `interrupted block-walking' policies combines these merits of global optimality and of compactness. [less ▲]

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See detailLacunary wavelet series on Cantor sets
Esser, Céline ULg

E-print/Working paper (2015)

We construct functions with prescribed multifractal spectra which satisfy the leaders profile method.

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See detailSocial Enterprise in Belgium: A Diversity of Roots, Models and Fields
Huybrechts, Benjamin ULg

E-print/Working paper (2015)

This working paper is structured as follows. The first introductory section reviews the main historical roots that have led to the emergence of a diversity of models related to social enterprise and the ... [more ▼]

This working paper is structured as follows. The first introductory section reviews the main historical roots that have led to the emergence of a diversity of models related to social enterprise and the social economy in Belgium. Next, the second section sketches the main features of these models in terms of legal forms, types of social missions addressed, governance dynamics and resources. In the third section, these models are then illustrated in different fields of activity both established and emerging. Finally, the fourth section proposes a transversal analysis of the main trends and challenges facing the development and coexistence of the different models. [less ▲]

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See detailCritical analysis and alternative processing of Type Ia supernovae data
Hauret, Clémentine ULg; Magain, Pierre ULg

E-print/Working paper (2015)

Context: Type Ia Supernovae (SNIa) observations in the late 90’s were the first hints for an accelerated expansion of our Universe. Today, hundreds of objects have been observed and seem to confirm the ... [more ▼]

Context: Type Ia Supernovae (SNIa) observations in the late 90’s were the first hints for an accelerated expansion of our Universe. Today, hundreds of objects have been observed and seem to confirm the flat LambdaCDM model as the cosmological model best representing our Universe. Aims: We study the SNIa observations gathered in the Union 2.1 and in the JLA compilations. By analyzing correlations and different ways of comparing cosmological models to the data, we bring to light some statistical biases, due to the current way of computing SNIa luminosity corrections for light-curve shape, color and host galaxy mass. Methods: We suggest an alternative, safer and model-independent methodology to calibrate the luminosity corrections, using only nearby SNIa. Results: With our recalibrated data, biases are strongly reduced. Moreover, open cosmological models are shown to be favoured over flat models (Omega_m,0 = 0.26+-0.08, Omega_Lambda,0 = 0.66+-0.12 for the SCP compilation and Omega_m,0 = 0.20+-0.08, Omega_Lambda,0 = 0.56+- 0.13 for the JLA one). Conclusions: The usual method to process SNIa data, i.e. simultaneously determining the parameters of the cosmological model and of the luminosity corrections on the full sample, is prone to bias the data in favour of the assumed cosmology, currently a flat LambdaCDM model, as well as to bias the cosmological parameters of the assumed model. [less ▲]

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See detailRevealing the crucial role of network rigidity on the fragility evolution of glasses
Yildirim, Can ULg; Raty, Jean-Yves ULg; Micoulaut, Mathieu

E-print/Working paper (2015)

If quenched fast enough, a liquid is able to avoid crystallization and will remain in a metastable supercooled state down to the glass transition, with an important increase in viscosity and relaxation ... [more ▼]

If quenched fast enough, a liquid is able to avoid crystallization and will remain in a metastable supercooled state down to the glass transition, with an important increase in viscosity and relaxation time towards equilibrium upon further cooling [1,2]. There are important differences in the way liquids relax as they approach the glass transition, rapid or slow variation in dynamic quantities under moderate temperature changes, and a simple means to quantify such variations is provided by the concept of "fragility". Here, we report molecular dynamics simulations of a typical network-forming glass, and find that the relaxation behaviour of the supercooled liquid is strongly correlated to the variation of rigidity with temperature and the spatial distribution of the corresponding topological constraints which, ultimately connect to fragility minima . This permits extending the fragility concept to aspects of topology/rigidity, and to the degree of homogeneity of the atomic-sale interactions for a variety of structural glasses. [less ▲]

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See detailReal options valuation under uncertainty
Platania, Federico ULg; Lambert, Marie ULg; Moreno, Manuel

E-print/Working paper (2015)

In this paper we develop a novel valuation model and methodology to value a pharmaceutical R&D project based on real options approach. The real options approach enables the possibility of optimally ... [more ▼]

In this paper we develop a novel valuation model and methodology to value a pharmaceutical R&D project based on real options approach. The real options approach enables the possibility of optimally abandon the project before completion whenever the investment cost turns out to be larger than the expected net cash flow stream. On the other hand, the proposed model accounts for two different sources of uncertainty, those are technical and economic risk. This model incorporates a novel economic state vector where each economic state captures the interaction among different market and economic forces using Fourier series as the particular basis for the economic function space. In this sense, Fourier series are considered as an aggregate of forces playing a relevant role in the process evolution determining the cash flow structure and also allowing us to properly define an economic scenario where the project will be developed. [less ▲]

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See detailTowards generic image classification: an extensive empirical study
Marée, Raphaël ULg; Geurts, Pierre ULg; Wehenkel, Louis ULg

E-print/Working paper (2014)

This paper considers the general problem of image classification without using any prior knowledge about image classes. We study variants of a method based on supervised learning whose common steps are ... [more ▼]

This paper considers the general problem of image classification without using any prior knowledge about image classes. We study variants of a method based on supervised learning whose common steps are the extraction of random subwindows described by raw pixel intensity values and the use of ensemble of extremely randomized trees to directly classify images or to learn image features. The influence of method parameters and variants is thoroughly evaluated so as to provide baselines and guidelines for future studies. Detailed results are provided on 80 publicly available datasets that depict very diverse types of images (more than 3800 image classes and over 1.5 million images). [less ▲]

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See detailLettre d'information du projet Dacefi-Synthèse & réalisations majeures
Meunier, Quentin; Morin, Amélie; Moumbougou, Carl et al

E-print/Working paper (2014)

Cette dernière lettre d'information du projet présente le bilan de ses réalisations et les avancées importantes du Gabon en termes de foresterie communautaire

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See detailProjet DACEFI 2. Principes fondateurs d'une forêt communautaire au Gabon. Outils de vulgarisation et de sensibilisation.
Meunier, Quentin; Boldrini, Sylvie; Larzillière, Adélaïde et al

E-print/Working paper (2014)

Faisant suite à une première phase (2006-2008), le projet pilote Développement d’Alternatives Communautaires à l’Exploitation Forestière Illégale (DACEFI-2, de 2010 à 2014) s’emploie à tester au Gabon la ... [more ▼]

Faisant suite à une première phase (2006-2008), le projet pilote Développement d’Alternatives Communautaires à l’Exploitation Forestière Illégale (DACEFI-2, de 2010 à 2014) s’emploie à tester au Gabon la mise en oeuvre des premières forêts communautaires. Un de ses objectifs majeurs consiste à tester le concept de foresterie communautaire au sein de plusieurs sites partenaires et de témoigner de l’expérience acquise afin que le Ministère en charge des Forêts adapte le cadre réglementaire. Quatre textes majeurs régissent la foresterie communautaire au Gabon, une loi (n°16/01), un décret d’application (n°1028/PR/MEFEPEPEN) et deux arrêtés (n°018/MEF/SG/DGF/DFC et n°106/MEFEPRN). Ils encadrent le processus de création d’une forêt communautaire. Afin de les rendre accessibles à un plus grand nombre, le projet DACEFI-2 s’est proposé de développer plusieurs supports de vulgarisation à destination des agents des Eaux et Forêts et des villageois. En éditant et en diffusant une série de posters, de films ou encore de bandes dessinées, le projet a contribué à faire connaître dans les provinces de l’Ogooué-Ivindo et du Moyen-Ogooué, l’esprit de ces textes légaux qui visent à favoriser le développement des communautés locales. Ce document de capitalisation présente une compilation des outils développés par les équipes du projet pour mener à bien cette campagne de sensibilisation. Nous abordons la gestion forestière durable par le prisme de la foresterie communautaire en évoquant l’esprit de la loi et les enjeux de la foresterie sociale. Nous proposons également une série de recommandations, basées sur notre expérience au Gabon, afin d’optimiser l’efficacité des communautés engagées dans ce processus. [less ▲]

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See detailLa mora débitoris chez Charles de Méan (esquisse)
Lagasse, Benoît ULg

E-print/Working paper (2014)

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See detailCorporate board attributes and conditional accounting conservatism: Evidence from French firms
Boussaid, Nabila ULg; Sougné, Danielle ULg; Hamza, Taher

E-print/Working paper (2014)

In this paper we investigate the relationship between boards of directors’ attributes and conditional accounting conservatism in the French context. Using a pooled regression model to evaluate this ... [more ▼]

In this paper we investigate the relationship between boards of directors’ attributes and conditional accounting conservatism in the French context. Using a pooled regression model to evaluate this relationship for the period 2009-2012, our empirical results can be summarized as follows. Firstly, greater board activity encourages more conservative reporting in financial statements. Secondly, greater board size diminishes conditional accounting conservatism. Lastly, there is a positive relationship between gender diversity and conservatism. To ensure robustness we have calculated our results using alternative measures of accounting conservatism, namely time series and accrual-based measures in addition to asymmetric timeliness of earnings. These findings suggest that boards of directors’ attributes are an important factor in determining the financial reporting quality of French firms. [less ▲]

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See detailMOLIERE PROJECT - Belgian National Report
Naedenoen, Frédéric ULg

E-print/Working paper (2014)

This document aims at introducing the restructuring phenomena in Belgium. It makes part of a larger project (called the MOLIERE project) undertaken by eleven European countries gathered to analyse ... [more ▼]

This document aims at introducing the restructuring phenomena in Belgium. It makes part of a larger project (called the MOLIERE project) undertaken by eleven European countries gathered to analyse restructurings. This national document follows a common reporting format: an introduction of the complex Belgian restructuring frameworks (1), a presentation of the main actors involved in the process (2), a synthesis of the measures created to anticipate change (3) and a synthesis of the measures established to manage change (4). [less ▲]

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See detailLe nouveau cadre d’action en matière de climat et d’énergie à l’horizon 2030
Habran, Maxime ULg

E-print/Working paper (2014)

Cette note a pour but de fournir un éclairage sur le nouveau cadre d'action européen en matière de climat et d'énergie

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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 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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Peer Reviewed
See detailEstimating the out-of-sample predictive ability of trading rules: a robust bootstrap approach
Hambuckers, julien ULg; Heuchenne, Cédric ULg

E-print/Working paper (2014)

In this paper, we estimate 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 ... [more ▼]

In this paper, we estimate 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 introduce an alternative bootstrap approach, based on the .632 bootstrap principle. This method enables to build in-sample and out-of-sample bootstrap data sets that do not overlap and exhibit the same time dependencies. We illustrate our methodology on IBM and Microsoft daily stock prices, where we compare 11 trading rules specifications. For the data sets considered, two different filter rule specifications have the highest out-of-sample mean excess returns. However, all tested rules cannot beat a simple buy-and-hold strategy when trading at a daily frequency. [less ▲]

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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 detailLettre d'information trimestrielle n° 15 du projet DACEFI 2
Boldrini, Sylvie; Meunier, Quentin; Moumbogou, Carl et al

E-print/Working paper (2014)

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See detailTowards a system of concept in GP/FM. Part I towards a specific indexation system. working draft
Jamoulle, Marc ULg

E-print/Working paper (2014)

EXECUTIVE SUMMARY Towards a system of concept on general practice / family medicine Part 1 Towards a specific indexation system in GP/FM Status of this document ; preliminary draft, not for diffusion ... [more ▼]

EXECUTIVE SUMMARY Towards a system of concept on general practice / family medicine Part 1 Towards a specific indexation system in GP/FM Status of this document ; preliminary draft, not for diffusion Intended audience : Members of the board of the PhD thesis of Marc Jamoulle, department of general practice, Liege University and experts in the field contacted by the author Background :Thousands of general practitioners/ family doctors are gathering each year in local, national or international congresses. They are exchanging thoughts, researches and methods through thousands of communications in various formats; posters, oral communications, workshops and so on. Although this huge collection of bottom-up knowledge is sometimes available through Internet sites, there is no specific indexation system allowing a real knowledge management of the exposed works. Consequently the information could not be reached, which don’t favor the exchange between researchers. The absence of a common indexation system is also a problem to organize the congresses and the participants have always difficulties to find communications relevant of their interest. The technology of semantic web and Linked data have emerged as a future solution to exchange data distributed in many languages between so many providers, the family physicians, spread around the globe. The considerable development of medical ontologies demonstrates the vitality of this field of discovery. Aim of the thesis; To find the best way to identify the main concepts effectively used by practicing GPs by the development of a system of classification embedded in the International classification of Primary Care aiming at retrieval of clinical and non-clinical issues addressed by the authors in their communications To propose a mapped terminology to this classification systems, in other words an ontology of GP/FM, to participle to a linked data based automatic or semi-automatic indexation of knowledge in GP/FM and its implementation in the realm of the semantic web. Content of the part 1 : the first steps towards a global classification system in GP/FM are related as well as previous experiences and difficulties with usual coding systems. The new information technology tools for information management are concisely described which permit the understanding of their importance in future research networks of knowledge in G/FM A comparison of the coding process and results of 6 congress of GP/FM in several countries and 4 languages has been performed to examine the internal reproducibility of the classifying system proposed. Next steps of the thesis are discussed of which first of them would be the constitution of an International research group. [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 detailLes métiers du développement durable
Cornet, Annie ULg; dubois, valérie

E-print/Working paper (2014)

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See detailProcedural rights in antitrust proceedings
Muheme, Daniel ULg; Neyrinck, Norman ULg; Petit, Nicolas ULg

E-print/Working paper (2014)

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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 detailHalf a century of French organizational sociology: methodological roots, compositionist branches
Dubois, Christophe ULg

E-print/Working paper (2014)

Now that 50 years have gone by since the publication of The Bureaucratic Phenomenon (French title: Le phénomène bureaucratique, 1963) by Michel Crozier, what is the legacy bequeathed by the sociology of ... [more ▼]

Now that 50 years have gone by since the publication of The Bureaucratic Phenomenon (French title: Le phénomène bureaucratique, 1963) by Michel Crozier, what is the legacy bequeathed by the sociology of organizations, in France and elsewhere, to today’s researchers? This contribution considers the premises of this methodology in order to establish two important achievements: the “decomposition” of the notions of organization, State and market; and the distinction of three dimensions of organizations, i.e. their managerial discourse, formal and informal structures. This article ends by considering one contemporary challenge this tradition of research has to face: how to account for the mechanisms of collective action, in order to take part in its composition? [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 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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Peer Reviewed
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 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 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 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 detailVisibilité des femmes d'affaires dans la presse d'affaires francophone belge
Cornet, Annie ULg; dubois, valérie

E-print/Working paper (2014)

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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 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 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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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 detailVorosweep: a fast generalized crystal growing Voronoi diagram generation algorithm
Mouton, Thibaud; Béchet, Eric ULg

E-print/Working paper (2014)

We propose a new algorithm for generating quickly approximate generalized Voronoi diagrams of point sites associated to arbitrary convex distance metric in the Euclidian plane. This algorithm produces ... [more ▼]

We propose a new algorithm for generating quickly approximate generalized Voronoi diagrams of point sites associated to arbitrary convex distance metric in the Euclidian plane. This algorithm produces connected cells by emulating the growth of crystals starting at the point sites, in order to reduce the complexity of the diagram. The main practical contribution is the Vorosweep package which is the reference implementation of the algorithm. Experimental results and benchmarks are given to demonstrate the versatility of this approach. [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 detailA multifractal formalism based on the Sν spaces: From theory to practice
Esser, Céline ULg; Kleyntssens, Thomas ULg; Nicolay, Samuel ULg

E-print/Working paper (2014)

We present an implementation of a multifractal formalism based on the Sν spaces and show that it effectively gives the right Hölder spectrum in numerous cases. In particular, it allows to recover non ... [more ▼]

We present an implementation of a multifractal formalism based on the Sν spaces and show that it effectively gives the right Hölder spectrum in numerous cases. In particular, it allows to recover non-concave spectra, where other multifractal formalisms only lead to the concave hull of the spectra. [less ▲]

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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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