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See detailAura
Durand, Pascal ULg

E-print/Working paper (in press)

Entrée du Lexique Socius sur le concept d'Aura chez Walter Benjamin

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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 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 detailSome misunderstood or unknown tricks (XIII) (LaTeX)
Merciadri, Luca ULg

E-print/Working paper (2015)

We will here again consider many tips and tricks. This time, they will mostly come from Glad Deschrijver, TeX Tricks, 2011. (http://users.ugent.be/~gdschrij/LaTeX/textricks.html.) Tricks: vertically ... [more ▼]

We will here again consider many tips and tricks. This time, they will mostly come from Glad Deschrijver, TeX Tricks, 2011. (http://users.ugent.be/~gdschrij/LaTeX/textricks.html.) Tricks: vertically aligned itemize environments, allowing linebreaks after comma in math mode, writing under and over elements, and using stacks, footnotes with a new number at each section, footnotes in tabular, splitting algorithm environments on multiple pages, let " produce opening/closing quotation marks, indenting some text but not the first line, using diagonal dots positioned according to the opposite diagonal, using a centered verbatim environment, drawing a table with dashed lines, shaded cells and arrows pointing at a row and a column, correct spacing around square brackets (used for sets) in math mode. [less ▲]

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See detailSome misunderstood or unknown LaTeX tricks (XIV) and LaTeX learning curve
Merciadri, Luca ULg

E-print/Working paper (2015)

We will here give three tricks: i. using a personalized \overline, ii. boxing every digit of an integer, iii. using \scalebox. I will then expose my point of view about the LaTeX learning curve, and give ... [more ▼]

We will here give three tricks: i. using a personalized \overline, ii. boxing every digit of an integer, iii. using \scalebox. I will then expose my point of view about the LaTeX learning curve, and give some of the most common beginners’ mistakes. [less ▲]

See detailSome misunderstood or unknown LaTeX tricks (XV)
Merciadri, Luca ULg

E-print/Working paper (2015)

After having looked at about 150 StackExchange pages of 50 topics (that sums up to about 7500 topics’ names), I give you, in this article and in the next issue, the most interesting topics’ answers to my ... [more ▼]

After having looked at about 150 StackExchange pages of 50 topics (that sums up to about 7500 topics’ names), I give you, in this article and in the next issue, the most interesting topics’ answers to my eyes. We will first begin by two additions in regard to 31(3), 32(1). [less ▲]

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See detailSome misunderstood or unknown LaTeX tricks (XVI)
Merciadri, Luca ULg

E-print/Working paper (2015)

This is the second (and last) part of the tricks I found on StackExchange. First part began in the preceding issue. We will begin by a personal trick, and end by some inquiry about my LaTeX Tips & Tricks.

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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 detailDocuments as a source of information; Tabular packages' purposes, conflicts; Same space in matrices; Logic inferences
Merciadri, Luca ULg

E-print/Working paper (2015)

The various aspects of the title are considered.

Detailed reference viewed: 32 (16 ULg)
See detailSome misunderstood or unknown tricks (X) (LaTeX)
Merciadri, Luca ULg

E-print/Working paper (2015)

This is the 10th edition of my `Tips & Tricks.' This time, we shall first see how to write `dancing text,' roman numerals, how to draw under and over braces on same elements, and how to display aligned ... [more ▼]

This is the 10th edition of my `Tips & Tricks.' This time, we shall first see how to write `dancing text,' roman numerals, how to draw under and over braces on same elements, and how to display aligned (in)equations systems. We will then end by discussing on BibLaTeX and Biber, which constitute a promising alternative to BibTeX. [less ▲]

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See detailSome misunderstood or unknown tricks (XI) (LaTeX) and encoding issues (II)
Merciadri, Luca ULg

E-print/Working paper (2015)

Three subjects will be detailed: 1. Using LaTeX syntax as an unambiguous way to communicate, 2. Writing a bold \ell, 3. Fonts' encodings.

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See detailEntretien avec Kathryn Batchelor
Oumarou Mal Mazou, Rachid ULg

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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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 detailTopology on new sequence spaces defined with wavelet leaders
Bastin, Françoise ULg; Esser, Céline ULg; Simons, Laurent ULg

E-print/Working paper (2015)

Using wavelet leaders instead of wavelet coefficients, new sequence spaces of type Sν are defined and endowed with a natural topology. Some classical topological properties are then studied; in particular ... [more ▼]

Using wavelet leaders instead of wavelet coefficients, new sequence spaces of type Sν are defined and endowed with a natural topology. Some classical topological properties are then studied; in particular, a generic result about the asymptotic repartition of the wavelet leaders of a sequence in Lν is obtained. Eventually, comparisons and links with Oscillation spaces are also presented as well as with Sν spaces. [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 detailPolicy dialogue: What it is and how it can contribute to evidence-informed decision-making.
Rajan, D; El Husseiny, D; Porignon, Denis ULg et al

E-print/Working paper (2015)

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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 detailDetection of local outliers in spatial multivariate data
Ernst, Marie ULg; Haesbroeck, Gentiane ULg

E-print/Working paper (2014)

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 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 detailAspects juridiques de la fiscalité du logement en Wallonie
Bahi, Sacha; Bianchet, Bruno ULg; Farah, Jihad ULg et al

E-print/Working paper (2014)

Ce numéro des « Notes de recherche » synthétise un des volets d’une étude dont l’objet est « la fiscalité relative au logement et l’aménagement du territoire ». Or, afin de bien appréhender les tenants et ... [more ▼]

Ce numéro des « Notes de recherche » synthétise un des volets d’une étude dont l’objet est « la fiscalité relative au logement et l’aménagement du territoire ». Or, afin de bien appréhender les tenants et les aboutissants de cette causalité et, surtout, de formuler des recommandations et propositions relatives au système fiscal en regard d’objectifs territoriaux, une analyse approfondie du cadre juridique s’avère indispensable. Cet examen constitue, en soi, un tout cohérent auquel pourra se référer le praticien de la gestion territoriale. La présente réflexion vise ainsi à présenter les divers mécanismes juridiques qui constituent des impôts frappant les biens immobiliers affectés au logement en Wallonie. L’étude s’intéresse principalement au territoire géographique wallon et non pas au seul pouvoir taxateur : « Région wallonne ». La précision est d’importance, a fortiori depuis l’entrée en vigueur de la sixième Réforme de l’État qui élargit considérablement la compétence du législateur wallon en la matière. Sont donc traités dans ce cadre tant les impôts fédéraux que régionaux, sans oublier les diverses « taxes locales » propres à chacune des communes et provinces de Wallonie. Les impôts directs, comme les impôts indirects seront analysés. Partant de ce balayage législatif de lege lata, la réflexion s’efforce de faire ressortir les diverses nuances politiques qui se dégagent des impôts analysés. Le doigt est tantôt mis sur les lacunes légistiques des textes, tantôt sur les critiques jurisprudentielles adressées aux taxes, tantôt encore, sur les potentialités qu’offriraient la redéfinition ou le recalibrage d’un mécanisme existant. L’étude vise, lorsqu’une possibilité lui est laissée, à formuler des propositions de lege feranda afin d’affermir la légalité de certains mécanismes fiscaux et d’améliorer l’utilisation qui est faite de ceux-ci à l’heure actuelle. [less ▲]

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Peer Reviewed
See detailPremières mises en liberté avant jugement devant la Cour pénale internationale
Deprez, Christophe ULg

E-print/Working paper (2014)

Ce billet évoque les premières libérations avant jugement intervenues devant la Cour pénale internationale (octobre 2014). Après avoir été soumis à un comité de lecture, il a été publié sur le 'blogue' de ... [more ▼]

Ce billet évoque les premières libérations avant jugement intervenues devant la Cour pénale internationale (octobre 2014). Après avoir été soumis à un comité de lecture, il a été publié sur le 'blogue' de la Clinique de droit international pénal et humanitaire de l'Université de Laval. [less ▲]

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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 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 detailIllustration du rôle de la Cour constitutionnelle : si l'utilité publique n'est plus établie, les propriétaires d'un bien exproprié doivent recevoir leur bien en retour
Bouhon, Frédéric ULg

E-print/Working paper (2014)

Les législateurs sont-ils tout puissants ? Certes ils sont à la source de l’ensemble des règles de droit dans le pays puisque ce sont eux qui adoptent les lois, les décrets et les ordonnances et que les ... [more ▼]

Les législateurs sont-ils tout puissants ? Certes ils sont à la source de l’ensemble des règles de droit dans le pays puisque ce sont eux qui adoptent les lois, les décrets et les ordonnances et que les arrêtés et règlements élaborés par les gouvernements et les administrations doivent les respecter. Mais les lois, les décrets et les ordonnances doivent aussi se conformer à des règles supérieures qui s’imposent à eux, notamment à celles qui garantissent nos droits fondamentaux, et ce sous le contrôle de la Cour constitutionnelle. Un tout récent arrêt, portant le n° 132/2014 et prononcé le 25 septembre 2014 , en fournit une illustration assez simple en matière d’expropriation. [less ▲]

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See detailCompte rendu de Baetens (Jan), Pour en finir avec la poésie dite minimaliste
Demoulin, Laurent ULg

E-print/Working paper (2014)

Il s'agit d'un compte rendu de l'ouvrage de Jan Baetens intitulé "Pour en finir avec la poésie dite minimaliste" paru sur le site Contextes à la page http://contextes.revues.org/5982.

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

E-print/Working paper (2014)

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

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

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

E-print/Working paper (2014)

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

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

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See 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 detailRetrouvailles à vélo avec Dick Annegarn
Demoulin, Laurent ULg

E-print/Working paper (2014)

Le nouveau CD de Dick Annegarn, Vélo va (2014), offre à son auditeur, à travers un bel échantillon de dix chansons, un aperçu des différentes facettes de l’art de l’auteur-compositeur-interprète.

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See detailSome misunderstood or unknown tricks (IX) (LaTeX)
Merciadri, Luca ULg

E-print/Working paper (2014)

We describe here how to display date & time in a standard format, write (draw) dash integrals, number rows in tables, use unhabitual punctuation marks: interrobang and percontation point, draw dependency ... [more ▼]

We describe here how to display date & time in a standard format, write (draw) dash integrals, number rows in tables, use unhabitual punctuation marks: interrobang and percontation point, draw dependency arrows, distinguish between ConTeXt, LuaTeX, teTeX and XeTeX. The last section gives a LaTeX-related crossword puzzle. [less ▲]

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See detailPresidential election in Turkey: a wide range of intricate challenges ahead of the next president
Sisu, Madalina; Lika, Liridon ULg

E-print/Working paper (2014)

On 10 August 2014, Turkey will hold the first round of presidential election which are of specific importance, as its results will shape the country’s both domestic politics and external relations. This ... [more ▼]

On 10 August 2014, Turkey will hold the first round of presidential election which are of specific importance, as its results will shape the country’s both domestic politics and external relations. This paper discusses the key challenges which Turkey’s next president must undertake. The domestic challenges range from revision of Constitution, Kurdish peace process and economic growth to polarization of society, freedom of judiciary, separation of powers and civil liberties. In the external relations area, the principal challenges are the worsening of country’s relations with its neighbours, security threats and the stalemate of the EU integration. Several domestic and external challenges are inter-related: for instance, the freedom of judiciary, separation of powers and civil liberties affect the EU integration process; the political uncertainty relates to economic growth and foreign investments; the Kurdish peace process impacts on the external security issues; the economic factors influence the relations with the Kurdistan Regional Government and Iraq’s central government; the Syrian crisis raises new challenges with regard to the Syrian refugees in Turkey. Therefore, addressing Turkey’s current domestic and external challenges will be a long, puzzling and often conflicting-results process. [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 detailEn attendant Toussaint
Demoulin, Laurent ULg

E-print/Working paper (2014)

Présentation et analyse de deux courtes pièces, Rideau et Ni l'un ni l'autre, écrites par Jean-Philippe Toussaint en 1981, quand il était un jeune auteur inconnu influencé par Samuel Beckett.

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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 detailNew Orleans Jazz & Heritage Festival 2014
Sacré, Robert ULg

E-print/Working paper (2014)

Compte rendu du NOLA Jazz & Heritage Festival avril-mai 2014 , avec photos

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See detailChina, 1978-2013: from one Plenum to another. Reflections on hopes and constraints for reform in the Xi Jingping era
Florence, Eric ULg

E-print/Working paper (2014)

Why is it so difficult to talk about China in a nuanced and contrasting manner without falling back on superlatives and generalisations? In about thirty years, China’s GDP per capita has multiplied by ... [more ▼]

Why is it so difficult to talk about China in a nuanced and contrasting manner without falling back on superlatives and generalisations? In about thirty years, China’s GDP per capita has multiplied by eight. From a marginal economic power during the Maoist period (1949-1978), China is now ranked tenth in terms of global economic weight. “Wealth and power” (fu qiang) is the expression that embodies China’s quest for modernity since the second half of the 19th century, when China was still under the yoke of the West. This ambition is still at the heart of the “Chinese dream of rejuvenation of the Chinese nation” dear to Xi Jinping, which he set out during the Third Plenum of the 18th Central Committee of the Chinese Communist Party. But focusing only on this vision of “wealth and power” takes us back to one of the most common ways of representing China: reducing the ongoing socio-economic changes and dynamics to a set of numeric values, ultimately reified and homogenised. The increased power and internationalisation of the Chinese economy has prompted a combination of worry and enthusiasm. What does this imply about the paradigm shift in the way we portray this country? Perhaps it is still hard to leave behind the image of a subordinate, poor and voiceless China and consider the Chinese people as, at least, our equals. [less ▲]

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See detailL’Université de Liège pendant la guerre 1914-1918
Bechet, Christophe ULg

E-print/Working paper (2014)

Histoire de l'Université de Liège pendant la Grande Guerre, axée principalement sur le drame de la place du 20 août et l'occupation des locaux par l'armée allemande.

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See detailFonck meurt premier comme devant
Bechet, Christophe ULg

E-print/Working paper (2014)

Cet article revient sur le mythe du cavalier Fonck, premier soldat belge tué le 4 août 1914, sur la route Thimister-Battice

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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 detailLes parlements peuvent-ils encore valider les pouvoirs de leurs élus?
Bouhon, Frédéric ULg

E-print/Working paper (2014)

Les élections du 25 mai 2014 ont été suivies de diverses contestations sur certains aspects de leur déroulement, spécialement au stade de leur dépouillement. C'est l'occasion de faire le point sur la ... [more ▼]

Les élections du 25 mai 2014 ont été suivies de diverses contestations sur certains aspects de leur déroulement, spécialement au stade de leur dépouillement. C'est l'occasion de faire le point sur la prérogative des assemblées législatives belges de vérifier elles-mêmes la validité des pouvoirs de leurs membres. [less ▲]

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See detailThe binary near-Earth asteroid (175706) 1996 FG3 - An observational constraint on its orbital stability
Scheirich, P.; Pravec, P.; Jacobson, S. A. et al

E-print/Working paper (2014)

Using our photometric observations taken between April 1996 and January 2013 and other published data, we derive properties of the binary near-Earth asteroid (175706) 1996 FG3 including new measurements ... [more ▼]

Using our photometric observations taken between April 1996 and January 2013 and other published data, we derive properties of the binary near-Earth asteroid (175706) 1996 FG3 including new measurements constraining evolution of the mutual orbit with potential consequences for the entire binary asteroid population. We also refined previously determined values of parameters of both components, making 1996 FG3 one of the most well understood binary asteroid systems. We determined the orbital vector with a substantially greater accuracy than before and we also placed constraints on a stability of the orbit. Specifically, the ecliptic longitude and latitude of the orbital pole are 266{\deg} and -83{\deg}, respectively, with the mean radius of the uncertainty area of 4{\deg}, and the orbital period is 16.1508 +\- 0.0002 h (all uncertainties correspond to 3sigma). We looked for a quadratic drift of the mean anomaly of the satellite and obtained a value of 0.04 +\- 0.20 deg/yr^2, i.e., consistent with zero. The drift is substantially lower than predicted by the pure binary YORP (BYORP) theory of McMahon and Scheeres (McMahon, J., Scheeres, D. [2010]. Icarus 209, 494-509) and it is consistent with the theory of an equilibrium between BYORP and tidal torques for synchronous binary asteroids as proposed by Jacobson and Scheeres (Jacobson, S.A., Scheeres, D. [2011]. ApJ Letters, 736, L19). Based on the assumption of equilibrium, we derived a ratio of the quality factor and tidal Love number of Q/k = 2.4 x 10^5 uncertain by a factor of five. We also derived a product of the rigidity and quality factor of mu Q = 1.3 x 10^7 Pa using the theory that assumes an elastic response of the asteroid material to the tidal forces. This very low value indicates that the primary of 1996 FG3 is a 'rubble pile', and it also calls for a re-thinking of the tidal energy dissipation in close asteroid binary systems. [less ▲]

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See detailFederico García Lorca en Lieja
Francois, Jeromine ULg

E-print/Working paper (2014)

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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)

Detailed reference viewed: 21 (0 ULg)
See detailSome misunderstood or unknown tricks (VIII) and Turing-completeness (LaTeX)
Merciadri, Luca ULg

E-print/Working paper (2014)

We will begin by exposing new tricks, i.e. how to 1. write ‘closed’ square roots, 2. insert blank pages, 3. ask the reader to turn the page, 4. write bold words in an index, 5. divide a cell by a diagonal ... [more ▼]

We will begin by exposing new tricks, i.e. how to 1. write ‘closed’ square roots, 2. insert blank pages, 3. ask the reader to turn the page, 4. write bold words in an index, 5. divide a cell by a diagonal, 6. draw ‘product integrals,’ 7. understand what happens when \mathcal has a lower-case letter argument. We will then consider an uncommon example of what one can do with LaTeX, in link with its Turing completeness. [less ▲]

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

E-print/Working paper (2014)

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

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

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Peer Reviewed
See detailHexis
Durand, Pascal ULg

E-print/Working paper (2014)

Définition et discussion du concept d'« Hexis » dans la sociologie de Pierre Bourdieu.

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Peer Reviewed
See detailIllusio
Durand, Pascal ULg

E-print/Working paper (2014)

Définition et discussion du concept d'« Illusio » dans la sociologie de Pierre Bourdieu.

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Peer Reviewed
See detailCapital symbolique
Durand, Pascal ULg

E-print/Working paper (2014)

Présentation et discussion du concept de « Capital symbolique » dans la sociologie de Pierre Bourdieu.

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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 detailEstimation and approximation in nonlinear dynamic systems using quasilinearization
Frasso, Gianluca ULg; Jaeger, Jonathan ULg; Lambert, Philippe ULg

E-print/Working paper (2014)

Nonlinear (systems of) ordinary differential equations (ODEs) are common tools in the analysis of complex one-dimensional dynamic systems. In this paper we propose a smoothing approach regularized by a ... [more ▼]

Nonlinear (systems of) ordinary differential equations (ODEs) are common tools in the analysis of complex one-dimensional dynamic systems. In this paper we propose a smoothing approach regularized by a quasilinearized ODE-based penalty in order to approximate the state functions and estimate the parameters defining nonlinear differential systems from noisy data. Within the quasilinearized spline based framework, the estimation process reduces to a conditionally linear problem for the optimization of the spline coefficients. Furthermore, standard ODE compliance parameter(s) selection criteria are easily applicable and conditions on the state function(s) can be eventually imposed using soft or hard constraints. The approach is illustrated on real and simulated data. [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 detailClassifying pairs with trees for supervised biological network inference
Schrynemackers, Marie ULg; Wehenkel, Louis ULg; Madan Babu, Mohan et al

E-print/Working paper (2014)

Detailed reference viewed: 34 (11 ULg)
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See detailLe Parti Socialiste en 2014: un programme électoral en rupture avec les précédents ?
Piet, Grégory ULg; Dandoy, Régis

E-print/Working paper (2014)

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

E-print/Working paper (2014)

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

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

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

E-print/Working paper (2014)

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

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

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

E-print/Working paper (2014)

Detailed reference viewed: 18 (3 ULg)
See detailFrench Texts in Medieval Cambridge
Morato, Nicola ULg

E-print/Working paper (2014)

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

E-print/Working paper (2014)

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

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

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See detailHubble Space Telescope Near-IR Transmission Spectroscopy of the Super-Earth HD 97658b
Knutson, Heather A.; Dragomir, Diana; Kreidberg, Laura et al

E-print/Working paper (2014)

Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets ... [more ▼]

Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets have no direct solar system analogue, and are currently one of the least well-understood classes of extrasolar planets. Many super-Earths have average densities that are consistent with a broad range of bulk compositions, including both water-dominated worlds and rocky planets covered by a thick hydrogen and helium atmosphere. Measurements of the transmission spectra of these planets offer the opportunity to resolve this degeneracy by directly constraining the scale heights and corresponding mean molecular weights of their atmospheres. We present Hubble Space Telescope near-infrared spectroscopy of two transits of the newly discovered transiting super-Earth HD 97658b. We use the Wide Field Camera 3's scanning mode to measure the wavelength-dependent transit depth in thirty individual bandpasses. Our averaged differential transmission spectrum has a median 1 sigma uncertainty of 19 ppm in individual bins, making this the most precise observation of an exoplanetary transmission spectrum obtained with WFC3 to date. Our data are inconsistent with a cloud-free solar metallicity atmosphere at the 17 sigma level. They are a good match for flat models corresponding to either a metal-rich atmosphere or a solar metallicity atmosphere with a cloud or haze layer located at pressures of a mbar or higher. [less ▲]

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

E-print/Working paper (2014)

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See detailWASP-20b and WASP-28b: a hot Saturn and a hot Jupiter in near-aligned orbits around solar-type stars
Anderson, D. R.; Collier Cameron, A.; Hellier, C. et al

E-print/Working paper (2014)

We report the discovery of the planets WASP-20b and WASP-28b along with measurements of their sky-projected orbital obliquities. WASP-20b is an inflated, Saturn-mass planet (0.31 $M_{\rm Jup}$; 1.46 $R ... [more ▼]

We report the discovery of the planets WASP-20b and WASP-28b along with measurements of their sky-projected orbital obliquities. WASP-20b is an inflated, Saturn-mass planet (0.31 $M_{\rm Jup}$; 1.46 $R_{\rm Jup}$) in a 4.9-day, near-aligned ($\lambda = 8.1 \pm 3.6^\circ$) orbit around CD-24 102 ($V$=10.7; F9). WASP-28b is an inflated, Jupiter-mass planet (0.91 $M_{\rm Jup}$; 1.21 $R_{\rm Jup}$) in a 3.4-day, near-aligned ($\lambda = 8 \pm 18^\circ$) orbit around a $V$=12, F8 star. As intermediate-mass planets in short orbits around aged, cool stars ($7^{+2}_{-1}$ Gyr for WASP-20 and $5^{+3}_{-2}$ Gyr for WASP-28; both with $T_{\rm eff}$ < 6250 K), their orbital alignment is consistent with the hypothesis that close-in giant planets are scattered into eccentric orbits with random alignments, which are then circularised and aligned with their stars' spins via tidal dissipation. [less ▲]

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See detailEn el laboratorio de la ciencia ficción hispánica: una entrevista
Ceballos Viro, Alvaro ULg

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 detailZola in Sciascia. Una nota su Candido
Curreri, Luciano ULg

E-print/Working paper (2014)

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See detailVon Themara nach Belgrad und zurück: Burkhard Spinnens Roman "Nevena"
Dupont, Bruno ULg

E-print/Working paper (2014)

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See detailCerebral functional connectivity periodically (de)synchronizes with anatomical constraints
Liegeois, Raphaël ULg; Sepulchre, Rodolphe ULg; LAUREYS, Steven ULg

E-print/Working paper (2014)

This paper studies the link between resting-state functional connectivity (FC), measured by the correlations of the fMRI BOLD time courses, and structural connectivity (SC), estimated through fiber ... [more ▼]

This paper studies the link between resting-state functional connectivity (FC), measured by the correlations of the fMRI BOLD time courses, and structural connectivity (SC), estimated through fiber tractography. Instead of a static analysis based on the correlation between SC and the FC averaged over the entire fMRI time series, we propose a dynamic analysis, based on the time evolution of the correlation between SC and a suitably windowed FC. Assessing the statistical significance of the time series against random phase permutations, our data show a pronounced peak of significance for time window widths around 20-30 TR (40-60 sec). Using the appropriate window width, we show that FC patterns oscillate between phases of high modularity, primarily shaped by anatomy, and phases of low modularity, primarily shaped by inter-network connectivity. Building upon recent results in dynamic FC, this emphasizes the potential role of SC as a transitory architecture between different highly connected resting state FC patterns. Finally, we show that networks implied in consciousness-related processes, such as the default mode network (DMN), contribute more to these brain-level fluctuations compared to other networks, such as the motor or somatosensory networks. This suggests that the fluctuations between FC and SC are capturing mind-wandering effects. [less ▲]

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

E-print/Working paper (2014)

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

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

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See detailInflated discrete Beta regression models for Likert and discrete rating scale outcomes
Taverne, Cédric; Lambert, Philippe ULg

E-print/Working paper (2014)

Discrete ordinal responses such as Likert scales are regularly proposed in questionnaires and used as dependent variable in modeling. The response distribution for such scales is always discrete, with ... [more ▼]

Discrete ordinal responses such as Likert scales are regularly proposed in questionnaires and used as dependent variable in modeling. The response distribution for such scales is always discrete, with bounded support and often skewed. In addition, one particular level of the scale is frequently inflated as it cumulates respondents who invari- ably choose that particular level (typically the middle or one extreme of the scale) without hesitation with those who chose that alternative but might have selected a neighboring one. The inflated discrete beta regression (IDBR) model addresses those four critical characteristics that have never been taken into account simultaneously by existing models. The mean and the dispersion of rates are jointly regressed on covariates using an underlying beta distribution. The probability that choosers of the inflated level invariably make that choice is also regressed on covariates. Simulation studies used to evaluate the statistical properties of the IDBR model suggest that it produces more precise predictions than competing models. The ability to jointly model the location and dispersion of (the distribution of) an ordinal response, as well as to characterize the profile of subject selecting an ”inflated” alternative are the most relevant features of the IDBR model. It is illustrated with the analysis of the political positioning on a ”left-right” scale of the Belgian respondents in the 2012 European Social Survey. [less ▲]

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See detailIntentionality as Disposition
Boccaccini, Federico ULg

E-print/Working paper (2014)

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

E-print/Working paper (2014)

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

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

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

E-print/Working paper (2014)

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

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

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See detailLa psychologie morale de Brentano
Boccaccini, Federico ULg

E-print/Working paper (2014)

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See detailWhat roles for energy cooperatives in the diffusion of distributed generation technologies?
Bauwens, Thomas ULg

E-print/Working paper (2014)

Whereas a centralized model of electricity infrastructure is still dominant today, many scholars advocate the diffusion of distributed generation technologies, implying geographically dispersed and small ... [more ▼]

Whereas a centralized model of electricity infrastructure is still dominant today, many scholars advocate the diffusion of distributed generation technologies, implying geographically dispersed and small-scale generation units located close to consumers. However, there exist various barriers of different natures to a large-scale penetration of these technologies. In this article, we focus on the behavioral and psychological ones, emphasizing the roles that citizens have to play in this issue. More specifically, we explore a specific way of involving citizens in such diffusion, namely energy cooperatives. After presenting the driving forces of the emergence of cooperative firms in the energy sector, we examine the assets of the cooperative ownership structure from the perspectives of behavioral economics and social psychology. Our analysis enables us to build a model of how cooperatives may enhance consumer engagement in the diffusion of distributed generation technologies. This provides a basic theoretical framework for future empirical research. [less ▲]

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See detailIntegrating the weight of history into the alignment framework: the case of distributed generation technologies
Bauwens, Thomas ULg

E-print/Working paper (2014)

Whereas a centralized energy supply system is still dominant today, the energy sector is currently witnessing the development of small-scale and more geographically dispersed generation units, so-called ... [more ▼]

Whereas a centralized energy supply system is still dominant today, the energy sector is currently witnessing the development of small-scale and more geographically dispersed generation units, so-called distributed generation technologies. So-called "alignment framework" proposes a very useful approach to look at this evolution. Yet, we argue in this paper that this framework does not fully take into account the inertia associated with past technological and institutional choices that may hinder future changes. Relying on the concept of socio-technical lock-in, we illustrate this point with the case of the diffusion of distributed generation technologies. Based on this analysis, we propose an adaptation of the alignment framework to integrate these elements. [less ▲]

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