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Finding a collective set of items: From proportional multirepresentation to group recommendation
No full textWe consider the following problem: There is a set of items (e.g., movies) and a group of agents (e.g., passengers on a plane); each agent has some intrinsic utility for each of the items. Our goal is to pick a set of K items that maximize the total derived utility of all the agents (i.e., in our example we are to pick K movies that we put on the plane's entertainment system). However, the actual utility that an agent derives from a given item is only a fraction of its intrinsic one, and this fraction depends on how the agent ranks the item among the chosen, available, ones. We provide a formal specification of the model and provide concrete examples and settings where it is applicable. We show that the problem is hard in general, but we show a number of tractability results for its natural special cases.nonouirechercheInternationa
On the use of a multicriteria decision aiding tool for the evaluation of comfort
No full textin International Handbooks on Information SystemsIn this paper we present a real word application of multicriteria decision aiding for the evaluation of high speed trains comfort from passengers’s point of view. Our study is used as a feasibility analysis for the introduction of multicriteria tools in the SNCF. Our approach concerns different steps of a decision aiding procedure. We firstly define the complex notion of comfort and propose to use a hierarchical model for its representation. We then present in more detail the seating comfort by assigning value scales to its components. Our problem being a sorting problem and our data being very heterogeneous, we decide to use the ELECTRE TRI method for the aggregation of the components. The article presents how the decision parameters, such as thresholds, weights and limit profiles, of ELECTRE TRI are selected and conclude with three fictitious assignment examples.nonouirechercheInternationa
Protecting Privacy in the Cloud: Current Practices, Future Directions
No full textCloud computing has become popular because of its benefits to users, which include having access to the resources they need at any time without having to invest in or manage an extensive computing infrastructure. However, users also lose control of the systems they depend on, which creates privacy and security concerns.nonouinon-rechercheInternationa
Médiation et langage de conception
No full textGroupe de Linguistique appliquée des Télécommunications Mines et université de Padoue 17-19 juinsous pressenonnonrechercheInternationa
Ambiguity in problem framing as a barrier to collective actions: some hints from groundwater protection policy in the Apulia Region
No full textDifferences in problem framing and understanding are unavoidable in multi-actor decision-making processes, deeming ambiguous problem definitions and actions. The presence of ambiguity may have diverse implications. On the one hand, a diversity in frames can enhance the co-production of knowledge offering opportunities for innovative solutions. On the other hand, the presence of ambiguity can be a source of discrepancies or conflict in a group, hampering the implementation and/or reducing the effectiveness of environmental policy. This work demonstrates that neglecting ambiguity in problem framing leads decision-actors to simplify the interaction space by ignoring the role of some of the other decision-actors and/or making wrong assumptions about their mental models. Moreover, they act as if the system is as simple as the decision-actors presume it to be. To demonstrate these hypotheses, a Causal Loop Diagram method was implemented to investigate the policy resistance mechanisms hampering the implementation of sustainable groundwater abstraction policy in the Apulia Region (Southern Italy).nonouirechercheInternationa
Les OMD sont-ils remis en cause par la crise des matières premières ?
No full textnonouinon-rechercheNationa
Expressive Power of Weighted Propositional Formulas for Cardinal Preference Modelling
No full textAs proposed in various places, a set of propositional formulas, each associated with a numerical weight, can be used to model the preferences of an agent in combinatorial domains. If the range of possible choices can be represented by the set of possible assignments of propositional symbols to truth values, then the utility of an assignment is given by the sum of the weights of the formulas it satisfies. Our aim in this paper is twofold: (1) to establish correspondences between certain types of weighted formulas and well-known classes of utility functions (such as monotonic, concave or k-additive functions); and (2) to obtain results on the comparative succinctness of different types of weighted formulas for representing the same class of utility functions.ouinonouirechercheInternationa
Légitimation et communication sociétale : le cas Péchiney
No full textCet article consiste en une étude des pratiques de communication sociétale du groupe Péchiney au cours de la seconde moitié du 20e siècle. Nous nous interrogeons sur les déterminants d’une telle diffusion. Le cadre théorique mobilisé est la théorie de la légitimité : nous considérons la communication sociétale telle une stratégie de légitimation. A l’aide de la théorie du media agenda-setting, nous proposons également une mesure de la pression de l’opinion publique. Nos résultats montrent en particulier qu’un des objectifs de la communication sociétale est de répondre aux attentes de la société civile.This paper consists in a longitudinal study of corporate social disclosure (CSD) practices of Pechiney during the second part of the XXth century. The research aims at identifying the determinants of such practices. The objective is to understand the motivations of companies in disclosing non financial information. Our theoretical framework is derived from legitimacy theory. We argue that CSD can be considered as a legitimation strategy and we document the link between CSD practices and public’s concern.. Based on media agenda-setting theory, we suggest a measure of public pressure. Our results show that CSD is a means used by firms to inform its stakeholders and also to manage public impressions.ouinonouirechercheNationa
Covering a Graph with a Constrained Forest
No full textGiven an undirected graph on n vertices with weights on its edges, Min WCF(p) consists of computing a covering forest of minimum weight such that each of its tree components contains at least p vertices. It has been proved that Min WCF(p) is NP-hard for any p ≥ 4 (Imielinska et al., 1993) but -approximable (Goemans and Williamson, 1995). While Min WCF(2) is polynomial-time solvable, already the unweighted version of Min WCF(3) is NP-hard even on planar bipartite graphs of maximum degree 3. We prove here that for any p ≥ 4, the unweighted version is NP-hard, even for planar bipartite graphs of maximum degree 3; moreover, the unweighted version for any p ≥ 3 has no ptas for bipartite graphs of maximum degree 3. The latter theorem is the first-ever APX-hardness result on this problem. On the other hand, we show that Min WCF(p) is polynomial-time solvable on graphs with bounded treewidth, and for any p bounded by it has a ptas on planar graphs.ouinonouirechercheInternationa