Suchergebnisse

AbstractA model of a set of interacting sectors is proposed. Dynamic equations governing the motions of sectoral productions are chosen. A supplementary equation establishing equilibrium of the national budget is obtained. The contradictory effects of technical change on the economic system are studied, as this change destroys employment by replacing men with machines and computers and also creates new sectors and employment. The paper studies a particular case of an economic system in which technical change globally destroys employment. Stimulation of the economic system can be done either by inducement to consumption or by inducement to production. In order to maintain total consumption and production, the paper shows that it is necessary to increase the purchase power of consumers and to create new sectors absorbing a lot of working hours per production unit. To obtain this, good quality products needing a lot of working hours must gradually replace all identical factory products needing less and less working hours.

AbstractPhysical and biological systems are composed with many levels of organization. To these different levels of organization are associated different levels of description, i.e. large classes of models relative to each of these levels. For instance, in ecology, roughly one distinguishes three levels of organization, the individual level, the population level and the ecosystem level, and consequently three large classes of models may be found, individual strategy models, population dynamical models (like the Leslie model) and ecosystem dynamical models (like the Lotka‐Volterra model). In this work, we present general methods to jump from one level to the next. For a two level system, one obtains two weakly coupled sets of equations (each one being relative to each level). The coupling terms allow one to study the interactions between the levels. This general method is then applied to ecology (coupled individual and population levels), to molecular and cellular biology (coupled chemical and cellular levels), and to economics (coupled sectorial and regional levels). One of our particular interests is to be able to obtain experimental verifications of the inter‐level coupling effects, which means simultaneous using of experimental data relative to both levels for the same system.

A study of the problems which face the prospective authors of a survey or the present trends of res in the soc sci's. The choice of disciplines to be covered by the report & their classification will be more difficult than in the case of the natural sci's because of the many cases of interdisciplinary res. The importance of methodological trends is emphasized. Some proposals are forwarded re the collection of material, the drafting of synthetic texts, & the revision of the initial drafts are presented. Finally a few recommendations are made to states, nat'l, or internat'l org's active in the field of soc scis. AA.

AbstractFirstly, we study dynamical processes in a hierarchically organized set of interacting elements. We study inter‐levels couplings which can be of two types, bottom‐top and top‐bottom. We apply this general method to coupled individual and population dynamics in Ecology. We realize computer simulations of this example. The coupling between the two levels gives birth to nonlinear effects. Secondly, we study thermodynamical aspects and we show that the entropy of a hierarchically organized system is the sum of entropies associated to each of the hierarchical levels. We consider ensembles with equiprobable and non equiprobable states. These states probabilities are calculated from the transition graph of the dynamical model. In this way, we relate thermodynamical models of hierarchically organized systems to dynamical models. Then, we calculate the entropy variation resulting from a change in the transition graph of the dynamical model. We show that the entropy of a hierarchically organized system can be larger than the entropy of a non hierarchical system.

This second issue of the French Complex Systems Roadmap is the outcome of the Entretiens de Cargese 2008, an interdisciplinary brainstorming session organized over one week in 2008, jointly by RNSC, ISC-PIF and IXXI. It capitalizes on the first roadmap and gathers contributions of more than 70 scientists from major French institutions. The aim of this roadmap is to foster the coordination of the complex systems community on focused topics and questions, as well as to present contributions and challenges in the complex systems sciences and complexity science to the public, political and industrial spheres.