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Learning Ordinal Preferences on Multiattribute Domains: the Case of CP-Nets
No full textA recurrent issue in automated decision making is to extract a preference structure from a set of examples. In this paper, we investigate the problem of learningordinal preference orderings over discrete multattribute, or combinatorial,domains. Specifically, we concentrate on the learnability issue of conditional preference networks, or CP-nets, that have recently emerged as a popular graphicallanguage for representing ordinal preferences in a concise and intuitive manner.This paper provides results in both passive and active learning. In passive learning, the learner aims at finding a CP-net compatible with a given set of examples,while in active learning the learner searches for the cheapest interaction policy with the user for acquiring the target CP-net.ouinonouirechercheInternationa
Complexity and approximation of the constrained forest problem
No full textGiven an undirected graph on n vertices with weights on its edges, Min WCF (p) consists of computing a covering previous termforestnext term 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) [10]) but View the MathML source-approximable (Goemans and Williamson (1995) [9]). 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 previous termproblemnext term. 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 View the MathML source it has a ptas on planar graphs.ouinonouirechercheInternationa
Strategic Scheduling Games: Equilibria and Efficiency
No full textin Book series, Springer Optimization and Its Applications, Volume 60Motivated by today’s decentralized operation of interconnected computing platforms, classical task scheduling models are revisited under a game theoretic perspective. Instead of being designed by a central entity which aims at optimizing an aggregate efficiency measure, task allocations emerge through aggregated localized decisions taken by a group of autonomous self-interested agents. The outcome is sought as an equilibrium whose overall social efficiency typically diverges from the optimal group’s choice. This divergence, captured by a measure that came to be known as the Price of Anarchy, can be alleviated by local scheduling policies called Coordination Mechanisms. This chapter reviews standard task scheduling models, dedicated coordination mechanisms and their influence on the price of anarchy. It also exemplifies the design and analysis of coordination mechanisms on a particular scheduling model with setup times, and discusses open research questions.ouinonouirechercheInternationa
From Evidence-Based Policy-Making to Policy Analytics
No full textThe paper aims at addressing the problem of what makes specific aidingto decide within public policy making problem situations. Under such aperspective it analyses some basic concepts such as “public policy”, “deliberation”,“legitimation”, “accountability” and shows the necessity to expandthe concept of rationality which is expected to be behind the acceptability ofa public policy. We then analyse the more recent tentative to construct a rationalsupport to policy making, that is the “evidence-based policy making”approach. Despite the innovation introduced with this approach, we showthat it basically fails to address the deep reasons for which supporting thedesign, implementation and assessment of public policies is a hard problem.We finally show that we need to move one step ahead, specialising decisionaiding methodology to meet the policy cycle requirements: a demand forpolicy analytics.ouinonouirechercheInternationa
Judgment aggregation rules based on minimization
No full textMany voting rules are based on some minimization principle. Likewise, in the field of logic-based knowledge representation and reasoning, many belief change or inconsistency handling operators also make use of minimization. Surprisingly, minimization has not played a major role in the field of judgment aggregation, in spite of its proximity to voting theory and logic-based knowledge representation and reasoning. Here we make a step in this direction and study six judgment aggregation rules; two of them, based on distances, have been previously defined; the other four are new, and all inspired both by voting theory and knowledge representation and reasoning. We study the inclusion relationships between these rules and address some of their social choice theoretic properties.ouinonouirechercheInternationa
Lessons from The French Exception: How Firms Choose Between Unitary and Dual Boards
No full textMany governance reform proposals focus on strengthening board monitoring. In contrast, Adams and Ferreira (2007) and Harris and Raviv (2008) conclude that a passive board is often optimal. We examine determinants of board structure choice in France, where firms are free to choose between a unitary (passive) board and a dual (monitoring) board. We find firms with greater asymmetric information are likely to adopt a unitary board. Firms with a high potential for private benefit extraction are likely to adopt dual boards. Firms well monitored by financial market and institutional forces are less likely to have dual boards. Our results imply that freedom of contract about board structure is valuable for shareholders.ouinonouirechercheInternationa
Fair Cost-Benefit Evaluation of Health Care: a Case Study of Blood Pressure Lowering Drugs in France
No full textnonouirechercheInternationa
Perception du risque dépendance et demande d'assurance : une analyse à partir de l'enquête PATER
No full textDans la littérature économique, de nombreux travaux tentent d'expliquer pourquoi les individus s’assurent aussi peu contre la dépendance mais très peu d’études empiriques permettent de tester les différents mécanismes limitant la demande de couverture. Les travaux empiriques existants sont généralement menés sur données américaines. Dans cet article nous mettons à profit des données françaises issues de l’enquête PATER qui étudie les comportements d’épargne et de couverture face au risque dépendance des ménages. Cet article vise à enrichir la littérature existante en étudiant empiriquement le rôle de la perception du risque dans la décision de se couvrir contre le risque dépendance et en se fondant sur l’observation directe des préférences individuelles (aversion pour le risque et préférence pour le présent) que permet par l’enquête PATER. Les estimations économétriques menées conduisent à mettre en évidence, outre l’effet des caractéristiques sociodémographiques, le rôle des préférences à l’égard du risque et du temps dans les comportements de couverture. La préférence pour le présent aurait un rôle important dans la perception du risque dépendance tandis que l’aversion au risque expliquerait le fait de souscrire une assurance dépendance parmi ceux envisageant la possibilité d’être un jour dans une situation de dépendance.nonouirechercheNationa
Polyhedral Analysis and Branch-and-Cut for the Structural Analysis Problem
No full textIn this paper we consider the structural analysis problem for differential-algebraic systems with conditional equations. This consists, given a conditional differential-algebraic system, in verifying if the system is structurally solvable for every state, and if not in finding a state in which the system is structurally singular. In this paper we study this problem from a polyhedral point of view. We identify some classes of valid inequalities and characterize when these inequalities define facets for the associated polytope. Moreover, we devise separation routines for these inequalities. Based on this, we develop a Branch-and-Cut algorithm and present some experimental results.ouinonouirechercheInternationa
Ground States for a Stationary Mean-Field Model for a Nucleon
No full textIn this paper we consider a variational problem related to a model for a nucleon interacting with the and mesons in the atomic nucleus. The model is relativistic, and we study it in a nuclear physics nonrelativistic limit, which is of a very different nature than the nonrelativistic limit in the atomic physics. Ground states are shown to exist for a large class of values for the parameters of the problem, which are determined by the values of some physical constants.nonnonouirechercheInternationa