Cyrille PIATECKI

One of the greatest difficulties meet on the labor market is that it ensures that all the people who want to work can find a job. But it is not the only one. A second difficulty consists to find a social arrangement which approaches as much as possible the social optimum without forgetting that the optimum can be reached with the rejection of certain candidacies. It seems impossible to solve a social optimum problem of the size of the french labor market because this one is furthermore constituted of 26 million job-seekers and that no computer is capable of managing the matching problem which, surprisingly is not of an excessive complexity-it is of order n 3-, but which quickly collides with the computational capacity of machines, however powerful they may be. It's the reason why it is essential to study restricted size markets, that is markets of less than 10000 job-seekers, to observe how practical solutions which can be organized as, for example, a geographical progressive balkanization either geographic or by skill level, leads to a departure from the Pareto optimum. In this context, this paper suggests to compare the level of efficiency of a decentralized actually practicable solution with the optimum which would be if only it was possible to collect all necessary information to implement and compute it.

Le problème de la coordination décentralisée des comportements individuels et de l'ajustement de l'économie vers un équilibre spécifique continue d'entretenir la scission classico-keynésienne : fonctionnant hors de l'équilibre ou possédant des capacités naturelles de sélection, l'économie est-elle apte à endogénéïser des externalités échappant totalement aux agents ? Le présent article étudie les capacités de coordination d'une économie stylisée au travers d'une dynamique évolutionnaire d'ajustement. En particulier, la prise en compte de coûts d'ajustement au sein de ce processus remet en cause l'efficience des optima de Pareto

Le blocus routier que doivent subir régulièrement les usagers des routes françaises est considéré comme une nuisance insupportable par tous les particuliers et toutes les entreprises européennes. Cependant, dans un contexte de concurrence forte sur les prix, il semble extrèmement difficile que l'État français intervienne sans déroger aux règlements de la Communauté Européenne. Cet article étudie la possibilité d'intervenir de la manière la plus légère possible de telle sorte que ces conflits récurrents cessent dans le cadre d'un jeu évolutionnaire dans lequel les entreprises de transport peuvent choisir d'afficher des salaires bas et donc des prix faibles ou des salaires élevés et donc des prix forts. Nous montrons qu'une simple prime versée aux entreprises à salaire élevé en cas de non attribution des contrats potentiels parce qu'elles ont été appariée avec une -- ou plusieurs -- entreprises à salaire faible, peut leur permettre de se maintenir sur le marché. Cependant si les entreprises adoptent leurs stratégies avec un délai de réaction, il est possible que la population des entreprises soit sujette à de très fortes fluctuations.

It may seem strange to a continental european that british island drive left. Nevertheless, it has been historically demonstrated that the initial norm was to drive left, which convey many physiological advantages. Some people defends the idea that the transition to a right norm is a history hazard linked to the will of the french 1792 revolutionary who want break with the ways and customs of the old system. In this paper, one defends an other conjecture which seems more likely : a cascade of important technical progress in the road and transportation system linked as much as to peoples than merchandises, may have as a consequence to carry the main part of the countries of the planet in a locked-in situation, that is to say a technology which, without any reason to subsist to day, has diffused and conquer

The double-entry bookkeeping promoted by Luca Pacioli in the fifteenth century could be considered a strong argument in behalf of the multiplicative calculus which can be developed from the Grossman and Katz non-newtonian calculus concept. In order to emphasize this statement we present a brief history of the accountancy in its early time and we make the point of Ellerman's research concerning the double-entry bookkeeping.

We derive a mesoscopic description of the behavior of a simple financial market where the agents can create their own portfolio between two investments alternatives: a stock and a bond. The model is derived starting from the Levy-Levy-Solomon microscopic model using the methods of kinetic theory and consists of a linear Boltzmann equation for the wealth distribution of the agents coupled with an equation for the price of the stock. From this model under a suitable scaling we derive a Fokker-Planck equation and show that the equation admits a self-similar lognormal behavior. Several numerical examples are also reported to validate our analysis.