Solutions diversification in a column generation algorithm

International audienceColumn generation algorithms have been specially designed for solving mathematical programs with a huge number of variables. Unfortunately, this method suffers from slow convergence that limits its efficiency and usability. Several accelerating approaches are proposed in the literature such as stabilization-based techniques. A more classical approach, known as "intensification, consists in inserting a set of columns instead of only the best one. Unfortunately, this intensication typically overloads the master problem, and generates a huge number of useless variables. This article covers some characteristics of the generated columns from theoretical and experimental points of view. Two selection criteria are compared. The first one is based on column reduced cost and the second on column structure. We conclude our study with computational experiments on two kinds of problems: the acyclic vehicle routing problem with time windows and the one-dimensional cutting stock. problem

LES EVOLUTIONS DE LA MESURE DE «LA NOUVELLE ECONOMIE » : BILAN ET ENJEUX

This article shows that the results of the studies on the relation between the use of Information an Communication Technologies (ITC) and economic performances are influenced by measuring instruments used. In the first part, we present the main results of these studies and we raise some methodological problems. In the second part, we focus on the question of the definition of the ICT sector and the emergence of the “information sector”. In a third part , we show that the results of empirical studies are sensitive to methodological choices made by statisticiansCet article montre que les résultats des études menées sur la relation entre utilisation des TIC et performances économiques sont influencés par les instruments de mesure et les méthodologies utilisées. Dans une première partie, nous présentons les principaux résultats des études et nous soulèverons quelques problèmes méthodologiques. Dans une seconde partie, nous étudions plus précisément les problèmes liés à la définition du secteur des TIC et les tentatives de construction d'un secteur consacré à «l'économie de l'information». Enfin, et dans une troisième partie, nous montrons que les résultats des études empiriques sont sensibles aux choix méthodologiques retenus par les statisticiens

DiscoClini : Une méthodologie pour l'extraction de relations linéaires dans des données de génomique médicale

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TaxoMap in the OAEI 2008 alignment contest

International audienceTaxoMap is an alignment tool which aim is to discover rich correspondences between concepts. It performs an oriented alignment (from a source to a target ontology) and takes into account labels and sub-class descriptions. Our participation in last year edition of the competition have put the emphasis on certain limits. TaxoMap 2 is a new implementation of TaxoMap that reduces significantly runtime and enables parameterization by specifying the ontology language and different thresholds used to extract different mapping relations. The new implementation stresses on terminological techniques, it takes into account synonymy, and multi-label description of concepts. Special effort was made to handle large-scale ontologies by partitioning input ontologies into modules to align. We conclude the paper by pointing out the necessary improvements that need to be made

Counting occurrences for a finite set of words: combinatorial methods

28 pagesInternational audienceIn this article, we give the multivariate generating function counting texts according to their length and to the number of occurrences of words from a finite set. The application of the inclusion- exclusion principle to word counting due to Goulden and Jackson (1979, 1983) is used to derive the result. Unlike some other techniques which suppose that the set of words is reduced (i.e., where no two words are factor of one another), the finite set can be chosen arbitrarily. Noonan and Zeilberger (1999) already provided a Maple package treating the non-reduced case, without giving an expression of the generating function or a detailed proof. We provide a complete proof validating the use of the inclusion-exclusion principle. We also restate in modern terms the normal limit laws theorems of Bender and Kochman (1993), emphasising on the underlying analytic mean shifting method

Didactique du lexique et problématique de l'unité lexicale : état d'une confusion

La didactique du lexique1 privilégie en général l'acquisition, c'est-à-dire l'accroissement du stock d'unités maîtrisées et employées par l'apprenant. Cette approche quantitative de la construction de la compétence repose sur un ensemble de prérequis dont l'utilité n'est plus à démontrer2 mais dont la pérennisation dans la suite des cursus s'avère particulièrement néfaste dès que l'apprenant est confronté à une exigence de technicité, notamment pour la préparation des concours de recrutement (Capes, Agrégation). Au coeur du problème, un déficit théorique important : l'absence d'une conceptualisation de l'unité lexicale. Nous pointerons ici brièvement deux difficultés majeures auxquelles conduit une telle conception : (i) la confusion entre l'unité lexicale (désormais UL) et d'une part le signe linguistique, de l'autre le mot ; (ii) la conception de la morphologie lexicale comme concaténation de morphèmes. Ces deux critiques ne sont pas nouvelles et n'ont pas perdu de leur pertinence car elles n'ont jamais été entendues en didactique, et peu au sein de la communauté des linguistes. Nous en rappellerons les tenants (première partie de l'étude) afin de proposer une procédure d'analyse du sens lexical qui s'appuiera sur la reformulation linguistique (seconde partie) et l'extraction (troisième partie)

Efficient Binary scheme for Training Heterogeneous Sensor Actor Networks

International audienceSensor networks are expected to evolve into long-lived, autonomous networked systems whose main mission is to provide in-situ users – called actors – with real-time information in support of specific goals supportive of their mission. The network is populated with a heterogeneous set of tiny sensors. The free sensors alternate between sleep and awake periods, under program control in response to computational and communication needs. The periodic sensors alternate between sleep periods and awake periods of predefined lengths, established at the fabrication time. The architectural model of an actor-centric network used in this work comprises in addition to the tiny sensors a set of mobile actors that organize and manage the sensors in their vicinity. We take the view that the sensors deployed are anonymous and unaware of their geographic location. Importantly, the sensors are not, a priori, organized into a network. It is, indeed, the interaction between the actors and the sensor population that organizes the sensors in a disk around each actor into a short-lived, mission-specific, network that exists for the purpose of serving the actor and that will be disbanded when the interaction terminates. The task of setting up this form of actor-centric network involves a training stage where the sensors acquire dynamic coordinates relative to the actor in their vicinity. The main contribution of this work is to propose an energy- efficient training protocol for actor-centric heterogeneous sensor networks. Our protocol outperforms all know training protocols in the number of sleep/awake transitions per sensor needed by the training process. Specifically, in the presence of $k$ coronas, no sensor will experience more than$\lceil log(k)\rceil$ sleep/awake transitions and awake periods

Random generation of possibly incomplete deterministic automata.

International audienceThis paper presents an efficient random generator, based on a Boltzmann sampler, for accessible, deterministic and possibly not complete automata

Vers une Ressource Prédicative pour l'Extraction d'Information

International audienceCet article présente une méthode pour construire, à partir d'une ressource lexicale prédicative existante, une ressource enrichie pouvant servir à une tâche d'extraction. Nous montrons les points forts et les lacunes de deux ressources existantes pour le Français : les Tables du LADL et Volem. Après avoir montré pourquoi nous avons sélectionné Volem, nous listons les données nécessaires à la tâche d'extraction d'information. Nous présentons le processus d'enrichissement de la ressource initiale et une évaluation, à travers une tâche d'extraction d'information concernant des textes de rachats d'entreprise

From crisis to crisis: the high cost of the post-soviet institutional lock-in

In this contribution, we shall try to characterise the Russian growth model the way it appears to have emerged in the 2000s, which we believe useful to explain the country's macroeconomic successes at an earlier stage as well as the severe problems it has to face now. We shall begin by presenting the macroeconomic indicators of the Russian Federation between the 1998 crash and up to the recent 2008 crisis, showing their very significant improvements in practically every area (part 1). However, the qualitative aspects of the economic growth suggest asking whether one the main reasons of Russia's economic success (high commodity prices) did not make it seriously sick with the “Dutch disease” (part 2). We shall further show that the impressive growth before the 2008 crisis was followed by a yet more impressive shock hitting the economy to the extent that very few analysts had imagined (part 3). We believe that the propagation of the crisis was amplified by the specific features of the capitalist system that emerged in Russia in the 2000s, particularly its “international regime” (part 4). We conclude our contribution by saying that the Russian model in the 2000 appeared to be intrinsically unstable before suggesting possible scenarios of finding paths to a sustainable growth model