Governing a Common-Pool Resource in a Directed Network

A local public-good game played on directed networks is analyzed. The model is motivated by one-way flows of hydrological influence between cities of a river basin that may shape the level of their contribution to the conservation of wetlands. It is shown that in many (but not all) directed networks, there exists an equilibrium, sometimes socially desirable, in which some stakeholders exert maximal effort and the others free ride. It is also shown that more directed links are not always better. Finally, the model is applied to the conservation of wetlands in the Gironde estuary (France).Common-pool Resource, Digraph, Cycle, Independent Set, Empirical Example

Influence and Social Tragedy in Networks

We model agents in a network game of strategic complements and negative externalities. Sufficient conditions for the existence of a unique Nash equilibrium and of a unique social optimum are established. Under these conditions, we find that players with more vulnerable locations in the network exert more effort at equilibrium, and that the most influential players should exert less effort at efficiency. We then find structural conditions under which each player exerts strictly more effort than her efficient level, whether the social optimum be interior or not

Welfare Analysis in Games with substitutabilities

This paper investigates the social optimum in network games of strategic substitutes and identifies how network structure shapes optimal policies. First, we show that the socially optimal profile is ob-tained through a combination of two opposite network effects, generated by the incoming and the outgoing weighted Bonacich centrality measures. Next, three different policies that restore the social optimum are derived, and the implications of the predecessor(s)-successor(s) relationship between the agents on each policy instrument are explored. Then, the link between optimal taxes and the density of the network is established

Equilibrium Existence and Uniqueness In Network Games with Additive Preferences

A directed network game of imperfect strategic substitutes with heterogeneous players is analyzed. We consider concave additive separable utility functions that encompass the quasi-linear ones. It is found that pure strategy Nash equilibria verify a non-linear complementarity problem. By requiring appropriate concavity in the utility functions, the existence of an equilibrium point is shown and equilibrium uniqueness is established with a P -matrix. Then, it appears that previous findings on network structure and sparsity hold for many more games

Equilibrium Uniqueness in Network Games with Strategic Substitutes

A local public goods game in weighted and directed networks is analyzed. Individual efforts are imperfect substitutes, players' preferences are heterogeneous and local externalities are non-uniform and asymmetric. Sufficient conditions under which the game admits a unique equilibrium are established in terms of the number of links between agents in the original network. It appears that these latter conditions for uniqueness are met if, and only if, the structure of relationships is \emph{productive}. That is, a parallel can be established between network games with strategic substitutes and the input-output theory pioneered by Wassily Leontief.local public goods ; Nash equilibrium ; generalized degree ; productive matrix ; Leontief model

Processus de sélection des technologies d'irrigation par les agriculteurs : entre interactions sociales et choix rationnels

This PhD thesis is devoted to the economic analysis of the process of irrigation technologies adoption by farmers under the effect of public incentives, imitation and private rationality. The aim of the first chapter is to analyze the factors affecting the diffusion of irrigation technologies in La Reunion Island (France). A survey on irrigated farms combined with a review of the empirical literature allow us to cluster these key factors within three axes: farmers' characteristics, farmers' adoption context characteristics and irrigation technology characteristics. Two theoretical frameworks conceptualizing these key factors are then discussed: the neoclassical approach and the evolutionary approach. In the second chapter, a conceptual framework is designed to assess the impact of public incentives on the selection process of a new irrigation technology by a population of farmers. A methodology, allowing estimating the parameters of diffusion, is developed and applied to the diffusion of the sprinkler integral cover system in La Reunion Island over period 1990-2006. Results show that the characteristic diffusion path is not perfectly symmetric and is significantly affected by equipment subsidies. In the third chapter, a probabilistic framework is tested for evaluating the role played by the determinants of the selection process of new irrigation technologies at the farm-level. Finally, this thesis defends the idea of a differentiation of the diffusion processes, and so of the relevant explicative models, according to the complexity of the innovative equipment.Cette thèse est consacrée à l'analyse économique du processus de changement technique des agriculteurs dans le domaine de l'irrigation sous l'effet d'incitations publiques, d'entraînement collectif et de logiques individuelles de profitabilité. Le premier chapitre analyse le déroulement et les déterminants de la diffusion des technologies d'irrigation améliorées à l'île de la Réunion. Une enquête auprès des irrigants combinée à une revue de la littérature empirique nous permet de regrouper ces facteurs-clés en trois axes : les caractéristiques des irrigants, les caractéristiques du contexte d'adoption des irrigants et les caractéristiques des technologies d'irrigation. Deux cadres théoriques complémentaires permettant de conceptualiser ces déterminants sont ensuite discutés : l'approche néoclassique et l'approche évolutionniste. Dans le second chapitre, une approche de diffusion globale est mise en œuvre pour évaluer l'impact des incitations publiques sur l'adoption d'une nouvelle technologie d'irrigation par une population d'agriculteurs. Une méthodologie d'estimation des paramètres de diffusion est développée et appliquée à la diffusion de l'aspersion en couverture intégrale à La Réunion de 1990 à 2006. Elle montre un effet positif significatif des subventions à cet équipement. Dans le troisième chapitre, un cadre conceptuel probabiliste est testé pour évaluer les déterminants du processus de sélection des nouvelles technologies d'irrigation à l'échelle de l'exploitation. Finalement, la thèse soutient l'idée d'une différenciation des processus, et donc des modèles explicatifs pertinents, selon la complexité de l'équipement innovant en diffusion

Warm-Glow Giving in Networks with Multiple Public Goods

This paper explores a voluntary contribution game in the presence of warm-glow effects. There are many public goods and each public good benefits a different group of players. The structure of the game induces a bipartite network structure, where players are listed on one side and the public good groups they form are listed on the other side. The main result of the paper shows the existence and uniqueness of a Nash equilibrium. The unique Nash equilibrium is also shown to be locally asymptotically stable. Then the paper provides some comparative statics analysis regarding pure redistribution, taxation and subsidies. It appears that small redistributions of wealth may sometimes be neutral, but generally, the effects of redistributive policies depend on how public good groups are related in the contribution network structure

La diffusion de technologies d'irrigation économes en eau à l'île de la Réunion

The aim of this paper is to identify and conceptualize factors affecting the diffusion of water-saving irrigation technologies in Reunion Island. A survey of 116 irrigated farms, combined with a review of the literature, allow us to sort these key factors within three axes : farmers characteristics, characteristics of the farmers? adoption context and characteristics of the water-saving irrigation technologies. Two theoretical frameworks are then introduced : the neoclassical theory and the evolutionary approach. The complementarity of each framework is shown : while the diffusion of improved sprinkler seems to comply with criteria of neoclassical diffusion, the low adoption of drip irrigation seems to depend on evolutionary factors.technological diffusion, adoption decision, neoclassical modelling, evolutionary approach