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This paper examines the interaction between two random processes: (1) a process of technological competition among several mature polluting technologies and a new technology which is environmentally friendly, but the cost of which depends on the adoption rate; (2) a random process of learning about the environmental impact of technologies by the public policy maker who may decide, according to the results, on taxation or prohibition of certain technologies. The ability of the public authorities to ensure the survival of the most environmentally friendly technology is analyzed. The role of various parameters is discussed, especially the interaction between the choice of risk thresholds which determine the intervention of public authorities (i.e. the implementation of the precaution principle) and the policy maker’s learning rate for environmental risks (i.e. the speed with which beliefs in risks regarding the most recent research results are adjusted). Some paradoxical effects arising from the implementation of the precaution principle on the survival of the most environmentally friendly technology are pointed out. The model illustrates problems encountered in practice like the choice of the European Union policy in the face of NOx emissions from cars.

The purpose of the model is to analyse the genesis and evolution of consumption oriented chat rooms in the Web space. We study an endogeneous consumption dynamics in which individuals make their buying decisions on the basis of a threefold information: their own consumption past experience (private information); an index of best sales (public information); advices that are available on evolutive Internet chat rooms (collective information). We discuss the properties of such a system as regards auto-organization: under which conditions chat rooms do they allow individual experiences to converge and aggregate into a genuine common knowledge leading to the emergence of an auto-organized pattern of consumption? Classification JEL : D1, D3, D7

The paper examines the long term problems of operational research through an analysis of OR as a system. The general environment will change as a result of the transformations occurring within the developed societies and of the mutations in the North-South relations; the interaction between OR, mass media and public opinion will be influenced by the emerging ideologies; the naive conceptions of the division of labour between policy makers and OR specialists will have to be revised as OR studies will be more and more developed for governments through national administrations, international organizations or public opinions; the formulation of goals will no longer be separated from the search for institutions liable to elaborate suitable goals; the tendency towards a systems analysis inspired by general systems theory should be reinforced; and finally the OR people will have to rethink the relations between their applied studies, the central core of OR itself and the various social sciences. Time seems to have come for an epistemology and a prospective study of OR.

OPERATIONAL RESEARCH at the national level in France is conditioned by the existence of the Commissariat au Plan. It is therefore important to know the status and nature of this body. The Ministries of the French Government administer national policies in health, education, and so on-as do their British counterparts. Like them also, some departments engage directly in economic activity: the post office and public works are shared examples; the tobacco monopoly run by the Ministry of Finance is an exception. Big national undertakings in France are also subject to government control. Some (atomic energy; space research) are strictly controlled by the administration. Others are more nearly autonomous (coal, electricity, railways), and these include some competitive organizations (Renault, the Compagnie Frangaise des Petroles). A national plan has been created to facilitate the development of the economy; the plan is formulated, and its implementation is supervised, by the Commissariat au Plan. The Commissariat, which was created in 1946, is the direct responsibility of the Prime Minister. Its senior staff is limited to 40 people apart from junior personnel. The Plan works with the help of 22 commissions and of working parties which grow out of the commissions. The people who form the commissions of the Plan are officials of the Ministries and the government agencies, together with representatives from public companies, private companies and trade associations. In compiling their reports these commissions often ask for studies to be carried out. Once these would have been financed by the relevant enterprises or agencies, but the Plan is now beginning to have its own funds for this purpose.