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2002


    

Session MB2 - Énergie, ressources et environnement II / Energy, Resources and Environment II

Day Monday, May 05, 2003
Room A.L. Van Houtte
President Guiomar Martin-Herran

Presentations

14:45 Stability and Optimal Control in Cooperative Dynamic Games of Sustainable Resource Management
  Jürgen Scheffran, Potsdam Institute for Climate Impact Research, Telegrafenberg A31, P.O. Box 60 12 03, 14412 Potsdam, Germany

Conditions for sustainable resource management are analyzed with a cooperative dynamic game in which players allocate their power resources to a set of actions to achieve target values in system space. Adapting power resources to reaction lines depending on other players actions leads to a state-dependent time-discrete dynamic system with constraints. The complexity and stability of the network architecture depends on the norm of the interaction matrix which is controlled by the action priorities of the players. Cooperative stabilization of the Nash equilibria leads to a multi-criteria vector optimization problem of finding the Pareto frontier in the allocation simplex for each time step. Negotiations on the amount and allocation of power resources helps to achieve a combination of objectives within the stability limits. Coalition formation and distribution of value gains provide a mechanism to achieve a cost-minimal solution in control space. The framework is applied to sustainable resource management (with a focus on fishery) where major players are competing firms using investment to generate profits, consumers allocating their income to goods on a market, and political institutions influencing the relationship between ecological and economic systems. Learning, mutual adaptation and negotiations on fair benefit-cost ratios are instruments to move from the exploitation to the sustainable use of natural resources. Computer simulation describes the self-organizing coalition-formation process from unilateral action to multilateral cooperation.


15:10 Slowing Deforestation Pace through Subsidies: A Differential Game
  Karima Fredj, HEC Montréal, GERAD et Économie appliquée, 3000, ch. de la Côte-Sainte-Catherine, Montréal, Québec, Canada, H3T 3A7
Guiomar Martin-Herran, Universidad de Valladolid, Spain
Georges Zaccour, HEC Montréal, GERAD et Marketing, 3000, ch. de la Côte-Sainte-Catherine, Montréal, Québec, Canada, H3T 2A7

This paper deals with the issue of deforestation, one of the main global environmental problems. We consider two players having different utilities for forest conservation. The first one (call it North) represents a set of countries having as an objective to maximize the size of tropical forest at a certain time horizon. The (South) second player's revenue function involves a trade-off between forest exploitation and agricultural activities. We study two scenarios. In the first one, the assumption is a laissez-faire policy, where the South solves an optimal control problem over a finite horizon. The revenue and optimal forest exploitation obtained represent a benchmark for the second scenario, where the North offers subsidies to the South to reduce the deforestation rate. The two scenarios are analyzed and compared in terms of strategies, outcomes and forest conservation.


15:35 Symmetry Analysis Applied to a Dynamic Resource Management Game
  Holger Meinhardt
Jürgen Scheffran, Potsdam Institute for Climate Impact Research, Telegrafenberg A31, P.O. Box 60 12 03, 14412 Potsdam, Germany

We study symmetries in a dynamical resource management problem for an incomplete renewable resource. To incorporate strategic interaction between agents we analyze a closed access common property. This enables us to consider whether the exploitation of the common pool resource can be destroyed by pursuing Nash feedback strategies. The system of partial differential equations which emerges in our framework of finite autonomous control is studied by computing in a first step the prolongation formula for the infinitesimal generators to obtain the determining equations. In the next step, we focus on group invariant solutions to study a system of differential equations involving fewer independent variables than the original system by means of bifurcation theory.


16:00 Deforestation and Foreign Transfers: A Differential Game Approach
  Guiomar Martin-Herran, Universidad de Valladolid, Spain
Pierre Cartigny, GREQAM, France
Estelle Motte, INRA, Montpellier, France
Mabel Tidball, INRA, Montpellier, France

In this paper, our concern is with deforestation as a global environmental issue. Foreign transfers from Northern countries to Southern countries have been proposed to deal with that issue. In order to take into account different information structures, we use a differential game approach where the two players are a donor community and a recipient country. We compare open-loop Nash equilibrium, feedback Nash equilibrium, Stackelberg equilibria and foreign transfers via a contract both from the environmental and economic point of view.