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Parameterized Inapproximability of Target Set Selection and Generalizations
No full textIn this paper, we consider the Target Set Selection problem: given a graph and a threshold value https://static-content.springer.com/image/chp%3A10.1007%2F978-3-319-08019-2_2/978-3-319-08019-2_2_IEq1_HTML.gif for each vertex v of the graph, find a minimum size vertex-subset to “activate” s.t. all the vertices of the graph are activated at the end of the propagation process. A vertex v is activated during the propagation process if at least https://static-content.springer.com/image/chp%3A10.1007%2F978-3-319-08019-2_2/978-3-319-08019-2_2_IEq2_HTML.gif of its neighbors are activated. This problem models several practical issues like faults in distributed networks or word-to-mouth recommendations in social networks. We show that for any functions f and ρ this problem cannot be approximated within a factor of ρ(k) in f(k) ·n O(1) time, unless FPT = W[P], even for restricted thresholds (namely constant and majority thresholds). We also study the cardinality constraint maximization and minimization versions of the problem for which we prove similar hardness results.nonouirechercheInternationa
Mathematical formulations for the Balanced Vertex k-Separator Problem
No full textGiven an indirected graph G = (V;E), a Vertex k-Separator is a subset of the vertex set V such that, when the separator is removed from the graph, the remaining vertices can be partitioned into k subsets that are pairwise edge-disconnected. In this paper we focus on the Balanced Vertex k-Separator Problem, i.e., the problem of finding a minimum cardinality separator such that the sizes of the resulting disconnected subsets are balanced. We present a compact Integer Linear Programming formulation for the problem, and present a polyhedral study of the associated polytope. We also present an Exponential-Size formulation, for which we derive a column generation and a branching scheme. Preliminary computational results are reported comparing the performance of the two formulations on a set of benchmark instances.nonouirechercheInternationa
Rigidity versus symmetry breaking via nonlinear flows on cylinders and Euclidean spaces
No full textThis paper is motivated by the characterization of the optimal symmetry breaking region in Caffarelli-Kohn-Nirenberg inequalities. As a consequence, optimal functions and sharp constants are computed in the symmetry region. The result solves a longstanding conjecture on the optimal symmetry range. As a byproduct of our method we obtain sharp estimates for the principal eigenvalue of Schrödinger operators on some non-flat non-compact manifolds, which to the best of our knowledge are new. The method relies on generalized entropy functionals for nonlinear diffusion equations. It opens a new area of research for approaches related to carré du champ methods on non-compact manifolds. However, key estimates depend as much on curvature properties as on purely nonlinear effects. The method is well adapted to functional inequalities involving simple weights and also applies to general cylinders. Beyond results on symmetry and symmetry breaking, and on optimal constants in functional inequalities, rigidity theorems for nonlinear elliptic equations can be deduced in rather general settings.nonnonrechercheInternationa
Inequality of Opportunity in Health in Indonesia
No full textLes pays en développement sont particulièrement concernés par la question des inégalités de santé et notamment celle de l’inégalité des chances. Néanmoins, très peu de travaux sont proposés dans le cadre des économies endéveloppement. Cet article étudie l’ampleur des inégalités des chances en matière de santé en Indonésie à partir de données recueillies par l’enquête IFLS (Indonesian Family Life Survey) de 2007 qui propose une information individuelle détaillée sur l’état de santé (bio-marqueurs et auto-évaluation) mais aussi sur l’environnement socioéconomique.Un indicateur synthétique continu de l’état de santé global calculé à partir d’un ensemble complet d’informations sur la santé est dans un premier temps proposé. Des méthodes paramétriques et non paramétriques sont ensuitemobilisées pour mesurer le niveau de l’inégalité des chances dans le domaine de la santé. Les résultats mettenten évidence une importante inégalité des chances relative à l’état de santé en Indonésie par rapport au niveau d’inégalité observée dans les pays européens. Le principal vecteur de transmission de l’inégalité est le statut de santé des parents (statut vital) et en particulier celui de la mère. L’impact du niveau d’éducation des parents estindirect (agissant sur l’environnement socio-économique, le statut marital et la migration des descendants) et est beaucoup plus faible que celui généralement observé dans des économies plus développées. Les disparités à long terme de l’état de santé liées à la religion, à la langue pratiquée et plus encore à la région d’habitation suggèrentque les variables d’appartenance communautaire sont prépondérantes pour analyser la question de l’équité en santé dans un pays en développement comme l’Indonésie.Whereas health equity issues are undoubtedly more relevant in developing countries, research on healthinequalities and, more specifically, on inequality of opportunity in the health dimension, remains scarce in this context. This paper explores the degree of inequality of opportunity in health in a developing country, using the 2007 Indonesian Family Life Survey, a large-scale survey with extremely rich information about individualhealth outcomes (biomarkers and self-reports) and individual circumstances.We compute a continuous synthetic index of global health status based on a comprehensive set of healthindicators and subsequently implement non-parametric and parametric methods in order to quantify the level ofinequality of opportunity in the health dimension. Our results show large inequality of opportunities in health inIndonesia, compared to European countries. Concerning transmission mechanisms, parental (particularly maternal) vital status appears as the main channel. Compared to what has been observed in more developed countries, the effect of parental education on health is relatively smaller, and mainly indirect (passing through descendants’ socioeconomic, marital and migration statuses), while the existence of long-term differences in health related to religion, language spoken and particularly province of location suggest a relatively higher relevance of community belonging variables for health equity in the context of a developing country asIndonesia.nonnonouirechercheInternationa
Consumer responses to elimination of overpackaging on private label products
No full textPurpose – Eliminating overpackaging is a central question in sustainable development, and poses a dilemma for retailers. Since packaging is a differentiation tool for private labels, eliminating it could limit the capacity to give those labels an equivalent image to national brands just as much as it could be a sustainable development opportunity and a positioning instrument. Drawing on the attribution theory framework, this article examines how eliminating overpackaging influences consumers’ perception of products sold under generic and mimic private labels, and their purchase intention. Methodology – This research uses a 2 (overpackaging: present vs. absent) x 2 (brand concept: generic vs. mimic private label) between-subjects experiment on a convenience sample of 217 French consumers. The conceptual framework was tested using ANCOVA and mediation analyses. Findings – Our experiment shows that eliminating overpackaging does have an influence on mimic private labels’ image, particularly on perceived quality, convenience and environmental friendliness. We also find that this influence negatively transfers to purchase intention for mimic private labels through lower perceived quality and convenience. No such effect appears for generic private labels’ image. Value – This study addresses an issue as yet unexplored in marketing – the effect of overpackaging on private label products – and proposes areas for managerial and societal reflection relevant to retail chains interested in eliminating overpackaging.nonouirechercheInternationa
Trade Performance of Free Trade Zones
No full textLes zones de libre-échange (ZFE) ont proliféré avec la libéralisation du commerce et de l’investissement. Elles jouent un rôle clé dans l’approfondissement de la chaîne mondiale de valeur.Toutefois, leur contribution au commerce international est peu connue, du fait du manqued’informations sur leur localisation et leur statut. Cet article tente d’améliorer leur connaissance enanalysant les performances commerciales des pays abritant des ZFE avec un focus sur les externalitéset les coûts dus aux distorsions. Nous avons ainsi construit une base de données originale sur les ZFEdéfinies comme des zones de transformation industrielle bénéficiant d’incitations sur les droits de douane. Nous montrons que les ZFE ne contribuent à augmenter le commerce du pays qu’en réduisant l’impact négatif du protectionnisme. En tant qu’importateurs de composants et de matières premières,elles augmentent les exportations des autres pays, ce qui confirme la contribution des ZFE à la chaîneglobale de valeur. Ce résultat est robuste avec d’autres spécifications du modèle, les erreurs et les biais dus aux problèmes de collecte des données et de composition de l’échantillon.Free trade zones (FTZ) have become widespread with the liberalisation of international trade andinvestment. They are a key player in the deepening of the global value chain (GVC). However, little isknown about their contribution to world trade due to a lack of information on their location and status.This paper sets out to improve knowledge in this area by analysing the trade performance of FTZcountries at macro-level with a focus on FTZ externalities and distortive costs. We have built anoriginal database of FTZs where we define them as processing zones benefiting from import tariffincentives. We show that FTZs raise trade only by easing the negative impact of protection. Asimporters of components and raw materials, they raise the rest of the world’s exports. This confirmsthe contribution of FTZs to the GVC. This result is robust to a change in the model specification,errors and bias due to data collection issues and sample composition.nonnonouirechercheInternationa
Bringing artifacts within institutional work. Arese’s artefacts and the institutionalization of socially responsible investment in France
No full textThe notion of institutional work has recently been developed to account for the purposive actions whereby actors attempt to create, maintain or disrupt institutions (Lawrence and Suddaby, 2006). It intends to complement the strong accounts of how institutions govern actions developed in institutional studies by accounts of how actors attempt to shape institutions. Examining the means by which actors do institutional work, researchers devoted to a great deal of attention to some specific means such as discourse while other means have been overlooked (Levy and Scully, 2007). In particular, the role of artifacts and their influence within institutionalization process has been repeatedly acknowledged to be a missing dimension of research on institutional work, and more generally of current institutional analysis (e.g. Lawrence and Suddaby, 2006; Pinch, 2008; Zilber, 2008). This is especially problematic as organized activities increasingly rely on the use of artifacts (Knorr-Cettina, 2007). Acknowledging the problem, an increasing number of authors have recently insist on the need to account for the role of artifacts when studying institutional work (e.g. Gawer and Philipps, 2013; Lawrence and Suddaby, 2006). However, despite such calls for more research to be done on the role of artifacts there is little empirical research about how artifacts are used in institutional work and how they influence institutionalization processes. The present paper seeks to address those calls and advance the integration of artifacts within research on institutional work by investigating how an artifact developed by an actor doing institutional work impacts the institutionalization of new practices. As such our work combines an interest for artifacts, with an interest for the institutionalization of practices. It provides novel insights to our understanding of the influence of artifacts within the institutionalization process, and contribute to bring materiality into the analysis of institutional work.More specifically, we draw from an in depth qualitative case study of the artifacts introduced by a non-financial rating agency named ARESE and how they influenced the institutionalization of socially responsible investment (SRI) within the French banks. Arese’s action was decisive to structure the activity, so that years 1997 to 2003, when the market really took off are commonly named the “Arese years” (Loiselet, 2003). Central to the action of Arese was the creation of artifacts to articulate their in-house system elaborated to measure corporate social performance and the demands of socially responsible fund managers. We listed three artifacts : rates available on Excel spreadsheet; a sheet with qualitative corporate data and social responsible indexes. We examine how those artifacts facilitate and shaped the institutionalization of SRI among the banks in France ou French financial market? Ou financial market in France? Ce qui permet d’englober d’autres acteurs que les banques?. We find that those artifacts had four types of effects on the institutionalization of SRI. First they legitimize SRI toward the large financial community. Second they favor the articulation of SRI with the existing routines of fund managers. Third, they limit the innonouirechercheInternationa
Comment les différences de parcours professionnels contribuent - elles aux écarts de santé entre femmes et hommes ?
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Perturbed Decomposition Algorithm applied to the multi-objective Traveling Salesman Problem
No full textDealing with multi-objective combinatorial optimization, this article proposes a new multi-objective set-based meta-heuristic named Perturbed Decomposition Algorithm (PDA). Combining ideas from decomposition methods, local search and data perturbation, PDA provides a 2-phase modular framework for finding an approximation of the Pareto front. The first phase decomposes the search into a number of linearly aggregated problems of the original multi-objective problem. The second phase conducts an iterative process: aggregated problems are first perturbed then selected and optimized by an efficient single-objective local search solver. Resulting solutions will serve as a starting point of a multi-objective local search procedure, called Pareto Local Search. After presenting a literature review of meta-heuristics on the multi-objective symmetric Traveling Salesman Problem (TSP), we conduct experiments on several instances of the bi-objective and tri-objective TSP. The experiments show that our proposed algorithm outperforms the best current methods on this problem.nonouirechercheInternationa