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Poverty Reduction and Growth Interactions: What Can Be Learned From the Syrian Experience?
No full textThe aim of this article is to analyse in depth the interactions of growth and poverty in Syria, which undertook reforms to reduce the government's involvement in the economy. During the 1996–2004 period, growth was pro-poor in ‘weak absolute’ terms but not in either relative or ‘strong absolute’ terms, owing to the increase in inequality. This can be explained partly by tax policies, but also by an unequal distribution of investment at the regional level. There was also a widening of the gap between urban and rural areas, mainly owing to a pattern of growth in which oil played an increasing role and agriculture a decreasing one. Agricultural and land-policy reforms could have had a negative impact on poverty, despite their positive effect on productivity.ouinonnonrechercheInternationa
Dependencies between players in Boolean games
No full textBoolean games are a logical setting for representing static games in a succinct way, taking advantage of the expressive power and succinctness of propositional logic. A Boolean game consists of a set of players, each of them controlling a set of propositional variables and having a specific goal expressed by a propositional formula, or more generally a specification of the player’s preference relation in some logical language for compact preference representation, such as prioritized goals. There is a lot of graphical structure hidden in a Boolean game: the satisfaction of each player’s goal depends on players whose actions have an influence on her goals. Exploiting this dependency structure facilitates the computation of pure Nash equilibria, by partly decomposing a game into several sub-games that are only loosely related.ouinonouirechercheInternationa
Boolean Games Revisited
No full textGame theory is a widely used formal model for studying strategical interactions between agents. Boolean games [8] aretwo players, zero-sum static games where players’ utility functionsare binary and described by a single propositional formula, and thestrategies available to a player consist of truth assignments to eachof a given set of propositional variables (the variables controlled bythe player.) We generalize the framework to n-players games whichare not necessarily zero-sum. We give simple characterizations ofNash equilibria and dominated strategies, and investigate the computational complexity of the related problems.ouinonouirechercheInternationa
Belief extrapolation (or how to reason about observations and unpredicted change)
No full textWe give a logical framework for reasoning with observations at different time points. We call belief extrapolation the process of completing initial belief sets stemming from observations by assuming minimal change. We give a general semantics and we propose several extrapolation operators. We study some key properties verified by these operators and we address computational issues. We study in detail the position of belief extrapolation with respect to revision and update: in particular, belief extrapolation is shown to be a specific form of time-stamped belief revision. Several related lines of work are positioned with respect to belief extrapolation.ouinonouirechercheInternationa
Increase in Life-Expectancy and Saving Behaviour
No full textThe age structure of the French population has been experiencing dramatic changes over the past decades and is likely to do so in a near future. The increasing proportion of the elder people may modify the savings behaviour of households. The level of savings, as well as its composition, may be altered by the ageing of the French population. This paper investigates the relationship between an increasing life expectancy and saving behaviour. We set up a life- cycle model in which the increase in life-expectancy is modelled as an increase in the probability of death at older ages. We introduce uncertainty as a consumption shock to stylise the fact that individuals may face an (uncertain) increase in expenditure for long term care (such as Alzheimer disease). We then show that, contrary to the standard life-cycle message, an increase in individual life-expectancy does not imply a decrease in saving or a more risk averse behaviour.ouinonouirechercheInternationa
Relative equilibria in continuous stellar dynamics
No full textWe study a three dimensional continuous model of gravitating matter rotating at constant angular velocity. In the rotating reference frame, by a finite dimensional reduction, we prove the existence of non radial stationary solutions whose supports are made of an arbitrarily large number of disjoint compact sets, in the low angular velocity and large scale limit. At first order, the solutions behave like point particles, thus making the link with the relative equilibria} in N-body dynamics.ouinonouirechercheInternationa
Decomposition of graphs: some polynomial cases
No full textWe study the problem of decomposing the vertex set V of a graphinto two parts (V1, V2) which induce subgraphs where each vertex vin V1 has degree at least a(v) and each vertex v in V2 has degreeat least b(v). We investigate several polynomial cases of this NP-complete problem. We give a polynomial-time algorithm for graphswith bounded treewidth which decides if a graph admits a decom-position and gives such a decomposition if it exists. We also givepolynomial-time algorithms that always find a decomposition for thefollowing two cases : triangle-free graphs such that d(v) ≥ a(v) + b(v)for all v ∈ V and graphs with girth at least 5 such that d(v) ≥a(v) + b(v) − 1 for all v ∈ V .ouinonouirechercheInternationa
Differential approximation for some routing problems
No full textWe study vehicle routing problems with constraints on the distance traveled by each vehicle or on the number of vehicles. The objective is to minimize the total distance traveled by vehicles. We design constant differential approximation algorithms for some of these problems. In particular we obtain differential bounds: 21 for Metric 3VRP, 53 for Metric 4VRP, 32 for Metric kVRP with k ≥ 5, 21 for the nonmetric case for any k ≥ 3, and 1/3 for Constrained VRP. We prove also that Min-Sum EkTSP is 32 differential approximable and has no differential approximation scheme, unless P = NP.ouinonouirechercheInternationa
Complexity of Most Vital Nodes for Independent Set in Graphs Related to Tree Structures
No full textGiven an undirected graph with weights on its vertices, the k most vital nodes independent set problem consists of determining a set of k vertices whose removal results in the greatest decrease in the maximum weight of independent sets. We also consider the complementary problem, minimum node blocker independent set that consists of removing a subset of vertices of minimum size such that the maximum weight of independent sets in the remaining graph is at most a specified value. We show that these problems are NP-hard on bipartite graphs but polynomial-time solvable on unweighted bipartite graphs. Furthermore, these problems are polynomial also on graphs of bounded treewidth and cographs. A result on the non-existence of a ptas is presented, too.ouinonouirechercheInternationa
Aléas de carrière et pensions de retraite
No full textLe système de retraite français établit un lien fort entre l'activité et la retraite, car les droits à pension s'acquièrent en fonction des périodes d'activité. En outre, les paramètres de calcul de la pension sont définis par référence à une carrière continue. En particulier, à partir de 2008 et jusqu'à la réforme de 2010, les pleins droits sont accordés à un individu totalisant au moins quarante années de durée d'assurance. Tout écart par rapport à cette carrière de référence est ainsi susceptible de modifier le montant de la pension que percevra l'assuré. Le système d'assurance vieillesse comporte cependant des dispositifs de solidarité, parmi lesquels l'octroi de droits à pension sans contrepartie de cotisations en cas d'interruption de carrière pour cause de maladie, de chômage ou pour l'éducation des enfants. L'analyse du déroulement de la carrière d'individus nés entre 1938 et 1948, effectuée à partir des calendriers rétrospectifs de l'enquête Patrimoine de l'Insee, met en évidence l'importance croissante des périodes de chômage, de travail à temps partiel et d'inactivité au fil des générations. L'étude de cas types de carrières marquées par ces différents aléas permet de déterminer dans quelle mesure le système de retraite en France corrige ces écarts à la carrière continue à temps complet. L'impact des aléas sur la pension est réduit quel que soit le profil de salaire grâce aux règles non contributives. L'ampleur de cette diminution est néanmoins différente entre la pension versée par le régime de base et celle des régimes complémentaires. Au final, les droits accordés au titre de l'éducation d'enfants permettent de limiter l'effet des périodes d'inactivité sur la pension. En revanche, les périodes de temps partiel peuvent donner lieu à une baisse de la pension en raison notamment de la perte de droits acquis au titre de la retraite complémentaire, particulièrement pour les cadres.ouinonouirechercheNationa