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Public Decision Processes: The Interaction Space Supporting Planner’s Activity
No full textThe aim of research is to test the model of interaction space as a tool to support the plan conception, in the context of a public decision process.Interaction space model allows to analyze the interaction mechanisms that a public process generally activates, and help the planner, or more generally the analyst, to understand what kind of development the process could have, in order to address its progress.The model has been tested during the planning process in Laurenzana, small village in the South of Italy. The paper describes the implementation and carries out some criticisms related to the not well structured relation between the space interaction model and the public decision process: once the interaction space is completely developed, the public process is generally at the beginning of implementation phase.nonouirechercheInternationa
Hedging under an expected loss constraint with small transaction costs
No full textWe consider the problem of option hedging in a market with proportional transaction costs. Since super-replication is very costly in such markets, we replace perfect hedging with an expected loss constraint. Asymptotic analysis for small transactions is used to obtain a tractable model. A general expansion theory is developed using the dynamic programming approach. Explicit formulae are also obtained in the special cases of an exponential or power loss function. As a corollary, we retrieve the asymptotics for the exponential utility indifference price.nonnonouirechercheInternationa
Fair Division under Ordinal Preferences: Computing Envy-Free Allocations of Indivisible Goods
No full textWe study the problem of fairly dividing a set of goods amongst a group of agents, when those agents have preferences that are ordinal relations over alternative bundles of goods (rather than utility functions) and when our knowledge of those preferences is incomplete. The incompleteness of the preferences stems from the fact that each agent reports their preferences by means of an expression of bounded size in a compact preference representation language. Specifically, we assume that each agent only provides a ranking of individual goods (rather than of bundles). In this context, we consider the algorithmic problem of deciding whether there exists an allocation that is possibly (or necessarily) envy-free, given the incomplete preference information available, if in addition some mild economic efficiency criteria need to be satisfied. We provide simple characterisations, giving rise to simple algorithms, for some instances of the problem, and computational complexity results, establishing the intractability of the problem, for others.nonouirechercheInternationa
Understanding the pace of deinstitutionalisation: the role and nature of cumulative actions in the case of asbestos in France
No full textEven when accelerated by a jolt, deinstitutionalisation is most often a long process constituted by short timestep and long timestep periods. Little has been said however to explain the pace of deinstitutionalisation and the factors that may accelerate or slow down this process. Not only strategic actions contribute to deinstitutionalisation. Multiple actions are involved and have an impact on the pace of deinstitutionalisation, depending on efforts of maintenance and disruption which may be opposed, isolated or cumulated. Based on Dorado’s profiles of institutional change, we draw out some core claims: (1) the pace of deinstitutionalisation is slower when defensive actions are related to leveraging- strategic actions; (2) the interaction between leverage-strategic actions and accumulating-sensemaking actions explains the creation of residues that later become essential in disrupting an institution; (3) long timestep periods of deinstitutionalisation are related to the tendency for disruptive agents to be weakened and dispersed due to their lack of strategic vision. We conclude by presenting “convening” as an efficient form of action to considerably slow down the deinstitutionalisation process. Our case is supported by a longitudinal analysis of the deinstitutionalisation of asbestos in France during the 20th century.nonnonrechercheInternationa
AGM Contraction and Revision of Rules
No full textIn this paper we study AGM contraction and revision of rules usinginput/output logical theories. We replace propositional formulas in the AGM framework of theory change by pairs of propositional formulas, representing the rule based character of theories, and we replace the classical consequence operator Cn by an input/output logic. The results in this paper suggest that, in general, results from belief base dynamics can be transferred to rule base dynamics, but that a similar transfer of AGM theory change to rule change is much more problematic. First, we generalise belief base contraction to rule base contraction, and show that two representationresults of Hansson still hold for rule base contraction. Second, we show that the six so-called basic postulates of AGM contraction are consistent only for some input/output logics, but not for others. In particular, we show that the notorious recovery postulate can be satisfied only by basic output, but not by simple-minded output. Third, we show how AGM rule revision can be defined in terms of AGM rule contraction using the Levi identity. We highlight various topics for further research.nonouirechercheInternationa
Lois techniciennes et droit à un procès équitable : le cas des lois de régulation économique
No full textnonouinon-rechercheNationa
A unified approach to a priori estimates for supersolutions of BSDEs in general filtrations
No full textWe provide a unified approach to a priori estimates for supersolutions of BSDEs in generalfiltrations, which may not be quasi left-continuous. As an example of application, we prove thatreflected BSDEs are well-posed in a general framework.nonnonrechercheInternationa
Conference Program Design with Single-Peaked and Single-Crossing Preferences
No full textWe consider the Conference Program Design (CPD) problem, a multi-round generalization of (the maximization versions of) q-Facility Location and the Chamberlin-Courant multi-winner election, introduced by (Caragiannis, Gourvès and Monnot, IJCAI 2016). CPD asks for the selection of kq items and their assignment to k disjoint sets of size q each. The agents receive utility only from their best item in each set and we want to maximize the total utility derived by all agents from all sets. Given that CPD is NP-hard for general utilities, we focus on utility functions that are either single-peaked or single-crossing. For general single-peaked utilities, we show that CPD is solvable in polynomial time and that Percentile Mechanisms are truthful. If the agent utilities are given by distances in the unit interval, we show that a Percentile Mechanism achieves an approximation ratio 1 / 3, if q=1, and at least (2q−3)/(2q−1), for any q≥2. On the negative side, we show that a generalization of CPD, where some items must be assigned to specific sets in the solution, is NP-hard for dichotomous single-peaked preferences. For single-crossing preferences, we present a dynamic programming exact algorithm that runs in polynomial time if k is constant.nonouirechercheInternationa
Finding large degree-anonymous subgraphs is hard
No full textA graph is said to be k-anonymous for an integer k, if for every vertex in the graph there are at least k−1k−1 other vertices with the same degree. We examine the computational complexity of making a given undirected graph k-anonymous either through at most s vertex deletions or through at most s edge deletions; the corresponding problem variants are denoted by Anonym V-Del and Anonym E-Del. We present a variety of hardness results, most of them hold for both problems. The two variants are intractable from the parameterized as well as from the approximation point of view. In particular, we show that both variants remain NP-hard on very restricted graph classes like trees even if k=2k=2. We further prove that both variants are W[1]-hard with respect to the combined parameter solutions size s and anonymity level k . With respect to approximability, we obtain hardness results showing that neither variant can be approximated in polynomial time within a factor better than View the MathML sourcen12 (unless P=NPP=NP). Furthermore, for the optimization variants where the solution size s is given and the task is to maximize the anonymity level k , this inapproximability result even holds if we allow a running time of f(s)⋅nO(1)f(s)⋅nO(1) for any computable function f. On the positive side, we classify both problem variants as fixed-parameter tractable with respect to the combined parameter solution size s and maximum degree Δ.nonouirechercheInternationa
Building Clusters with Lower-Bounded Sizes
No full textin Leibniz International Proceedings in Informatics (LIPICS), vol. 64Classical clustering problems search for a partition of objects into a fixed number of clusters. In many scenarios however the number of clusters is not known or necessarily fixed. Further, clusters are sometimes only considered to be of significance if they have a certain size. We discuss clustering into sets of minimum cardinality k without a fixed number of sets and present a general model for these types of problems. This general framework allows the comparison of different measures to assess the quality of a clustering. We specifically consider nine quality-measures and classify the complexity of the resulting problems with respect to k. Further, we derive some polynomial-time solvable cases for k = 2 with connections to matching-type problems which, among other graph problems, then are used to compute approximations for larger values of k.nonouirechercheInternationa