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The Lazy Bureaucrat Problem with Common Arrivals and Deadlines: Approximation and Mechanism Design
No full textin Springer series Lecture Notes in Computer Science, vol. 8070We study the Lazy Bureaucrat scheduling problem (Arkin, Bender, Mitchell and Skiena [1]) in the case of common arrivals and deadlines. In this case the goal is to select a subset of given jobs in such a way that the total processing time is minimized and no other job can fit into the schedule. Our contribution comprises a linear time 4/3-approximation algorithm and an FPTAS, which respectively improve on a linear time 2-approximation algorithm and a PTAS given for the more general case of common deadlines [2,3]. We then consider a selfish perspective, in which jobs are submitted by players who may falsely report larger processing times, and show a tight upper bound of 2 on the approximation ratio of strategyproof mechanisms, even randomized ones. We conclude by introducing a maximization version of the problem and a dedicated greedy algorithm.nonouirechercheInternationa
A Refined Complexity Analysis of Finding the Most Vital Edges for Undirected Shortest Paths
No full textin Springer series Lecture Notes in Computer Science, Vol. 9079We study the NP-hard Shortest Path Most Vital Edges problem arising in the context of analyzing network robustness. For an undirected graph with positive integer edge lengths and two designated vertices s and t, the goal is to delete as few edges as possible in order to increase the length of the (new) shortest st-path as much as possible. This scenario has been mostly studied from the viewpoint of approximation algorithms and heuristics, while we particularly introduce a parameterized and multivariate point of view. We derive refined tractability as well as hardness results, and identify numerous directions for future research. Among other things, we show that increasing the shortest path length by at least one is much easier than to increase it by at least two.nonouirechercheInternationa
Garantie de passif social et garantie d'éviction : la question du fait générateur
No full textNote sous Cour de cassation, Chambre commerciale, 3 mars 2015nonouinon-rechercheNationa
Refus de cerification et responsabilité du commissaire aux comptes
No full textNote sous Cour de cassation, Chambre commerciale, 18 février 2014nonouinon-rechercheNationa
The impact of price display on perceptions of luxury: a masstige perspective
No full textBased on two experimental studies in which college students participated, this paper investigates the impact of price display in the luxury sector on low-end brands perceived luxury and attitude. In Study 1, we show that price display is associated with higher perceived quality, uniqueness, and conspicuousness for a fictitious low-end brand. In Study 2, we confirm this positive influence for a real low-end brand, and show that it transfers to brand attitude through perceived quality and conspicuousness. In addition, Study 2 indicates no negative effect of price display on perceptions of luxury for a higher level brand. In a pioneering attempt to evaluate the effects of price display in the luxury sector, this paper adds value to the body of literature on luxury brand management. Besides, it provides insight to managers of luxury brands of different range levels on the effects of price display, a practice that develops as more and more luxury companies engage in masstige strategies or open commercial websites.nonnonrechercheInternationa
Query-based learning of acyclic conditional preference networks from noisy data
No full textConditional preference networks (CP-nets) provide a powerful, compact, and intuitive graphical tool to represent the preferences of a user. However learning such a structure is known to be a difficult problem due to its combinatorial nature. We propose in this paper a new, efficient, and robust query-based learning algorithm for acyclic CP-nets. In particular, our algorithm takes into account the incoherences in the user’s preferences or in noisy data by searching in a principled way the variables that condition the other ones. We provide complexity results of the algorithm, and demonstrate its efficiency through an empirical evaluation on synthetic and on real datasets.nonouirechercheInternationa
A variable neighborhood search algorithm for the surgery tactical planning problem
No full textWe address the tactical planning problem of surgeries that consists in building an admission plan of patients over a medium-term horizon planning so as to minimize over and under utilization of several resources such as operating theaters, beds and nursing care, compared with their target level of utilization. The problem is formulated as a mixed integer linear program for which exact solution methods fail to find an optimal solution in a reasonable execution time. We develop a Variable Neighborhood Search algorithm and show its ability to provide high quality solutions in short computational running times compared with CPLEX for numerous real-sized instances based on the surgery planning problem in a Dutch cardiothoracic center. Furthermore, with few parameters' settings and low computational memory requirements, this approach may easily be implemented in a decision support system for hospitals.nonnonrechercheInternationa
An Empirical Study on Factors of Perceived Walkability
No full textWe present preliminary results of a pilot empirical study designed to examine factors associated with pedestrians’ perception of walkability, i.e. the perception of the quality, comfort and pleasantness of streets, and their conductivity to walk. This empirical study contributes to the ongoing multidisciplinary effort to pin down factors, their relative importance and theirinteractions, relevant for pedestrians’ perception of walkability, that is to say, of the quality, comfort and pleasantness of streets, and their conductivity to walk. In attempt to describe and explain people’s propensity and decision to walk, their choices of pedestrian route and the qualitative perception thereof, scholars have examined a series of factors, related to individual characteristics (e.g. age, gender, income, etc.), mobility opportunities (e.g.availability of public transportation), trip types (purpose, frequency, available time, etc.), and features of the walking environment (Mateo-Babiano 2016). Our study focuses on this latter family of factors, related to the physical urban environment, and attempts to determine their correlation with the subjective, qualitative perception of the walking environment.nonouirechercheInternationa
Supporting environmental planning: Knowledge management through fuzzy cognitive mapping
No full textLecture Notes in Computer Science, Vol. 9320The inherently complex nature of the environmental domain requires that planning efforts become projects of participated, inclusive, multi-agent, multi-source knowledge building processes developed by the community. Knowledge is often hard to be processed, handled, formalized, modeled. Yet cognitive models are useful to avoid the typical unmanageability of domains with high complexity such as the environmental one, and enhance knowledge organization and management. We have investigated on the potentials of cognitive-mapping-based tools, particularly on cross impact evaluations, in the case study of Taranto (Italy). The process was aimed at building up future development scenarios in city neighborhoods, and fuzzy cognitive mapping were used to support decision-making by exploring cross impacts of possible policy perspectives. Although substantial results are rather general, the study proves to be interesting in enhancing the potentials of FCM-based approach to support decisionmaking, particularly when dealing with well-focused policy perspectives.nonouirechercheInternationa