New Approaches in Coalition Stability

In this paper we propose the state of art in the theory of coalitional games in effectiveness form without bargaining between coalitions. We study some solution concepts: The largest consistent set (Chwe, 1994); the largest cautious consistent set (Mauleon et al., 2004); the credible consistent set (Bhattacharya, 2002); standard stable behaviors (Xue, 1998). A series of examples, showing main features and differences between these solutions, are presented in order to outline some drawbacks and positive aspects in the philosophical framework of stability concepts.coalitonal games; stable sets; farsightedness.

International Environmental Agreement: a Dynamic Model of Emissions Reduction

We model an International Environmental Agreement as a two stages game: during the first stage each country decides whether or not to join the agreement while, in the second stage, the quantity of emissions reduction is choosen. Players determine their abatement levels in a dynamic setting, given the dynamics of pollution stock and the strategies of other countries. Players may act cooperatively, building coalitions and acting according to the interest of the coalition, or they make their choices taking care of their individual interest only. Countries can behave myopically or in a farsighted way. As a consequence, the size of stable coalition can completely change. A continuous time framework is choosen in the present paper and consequently the problem is studied by a differential game.IEA, Differential games, Coalition stability.

Competition and Cooperation in a dynamical model of natural resources

In this paper we propose a model describing the commercial exploitation of a common property renewable resource by a population of agents. Players can cooperate or compete; cooperators maximize the utility of their group while defectors maximize their own profit. The model provides for one utility function which can be used for every kind of player. Agents aren't assumed to be divided into the two groups from the beginning; by solving the static game we obtained the best response function of i-th player without making other agents positions. Then, the Nash equilibria we calculated point out how different strategies - all players cooperate, all players compete or players can be divided into cooperators and defectors - can coexist. In any case the total harvest depend on renewable resource stock, and it influences agents' positions. According to the Nash equilibria, harvested is arranged to fishing population dynamics and a complete analysis for the equilibria obtained and for their stability is proposed. The effects of the different Nash equilibria on the fish stock are compared showing the more stability in the cooperative case.Nash Equilibria, Resource Exploitation, Population Dynamics.

Cooperazione e competizione nello sfruttamento di una risorsa rinnovabile

In this paper we propose a static model describing the commercial exploitation of a common property renewable resource by a population of agents. Players can cooperate or compete; cooperators maximize the utility of their group while defectors maximize their own profit. Agents aren't assumed to be divided into the two groups from the beginning; by solving the static game we obtained the best response function of i-th player without making other agents positions. Then, the Nash equilibria we calculated point out how different strategies - all the players cooperate, all the players compete or players can be divided into cooperators and defectors - can coexist.Resource Exploitation, Game theory

Determinazione di strategie nello sfruttamento di una risorsa rinnovabile

In this paper we propose a static model describing the commercial exploitation of a common property renewable resource by a population of agents. Players can cooperate or compete; cooperators maximize the utility of their group while defectors maximize their own profit. The model provide for one utility function which can be used for every kind of player. Agents aren't assumed to be divided into the two groups from the beginning; by solving the static game we obtained the best response function of i-th player without making other agents positions. Then, the Nash equilibria we calculated point out how different strategies - all the players cooperate, all the players compete or players can be divided into cooperators and defectors - can coexist. In any case we have analyzed, it's possible to observe how the total harvest depend on renewable resource stock, and how it influences agents' positions. Keywords Resource Exploitation, Game Theory

Largest Consistent Set in International Environmental Agreements

In this paper we study the formation and the stability of International Environmental Agreements (IEAs) in a pollution abatement model with a quadratic cost function. Countries play a two-stage game: in the first stage each country decides to join or not the coalition while, in the -second stage, the quantity of pollution abatement is chosen. To analyze the stability of coalition structures in a multiple coalition game, we use the notion of the Largest Consistent Set (LCS) which allows players to be farsighted.In an abstract context, Chwe (1994) developed the concept of farsighted stability: an outcome is stable and it is in the LCS if and only if deviations from it or potential further deviations are not unanimously preferred to the original outcome by the coalition considering the deviations. Applying this notion of stability in the IEA context we assume that, when a country or a sub-coalition contemplate exiting or joining an agreement, it takes into account the reactions of other countries ignited by its own actions. We identify what would be the resulting stable structures and the LCS, examining the indicator of countries’ environmental awareness proposed by the model. A particular analysis is proposed about the Grand Coalition. Moreover, we present a handy Maple algorithm to compare the cost functions and to determine direct dominance.IEA; Farsightedness; Implementation.

Impact of migration on the occurrence of new cases of Chagas disease in Buenos Aires city, Argentina

Chagas disease, also known as American Trypanosomiasis, is endemic in the Americas, especially Central and South America. Chagas disease is a zoonotic disease caused by the parasite Trypanosoma cruzi. Most of the infections take place in children by vector or congenital transmission, with other modes of infection such as blood transfusion, organ transplants, and oral route being less frequent. In areas under vectorial control, congenital transmission is the most common way of accruing the diseaseFil: Moscatelli, Guillermo. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garcia Bournissen, Facundo. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Freillij, Hector. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Berenstein, Ada. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Tarlovsky, Ana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Moroni, Samanta. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Ballering, Griselda. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Biancardi, Miguel Angel. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Siniawski, Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Schwarcz, Marta. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Hernandez, Susana. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Espejo Cozzi, Andres. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; ArgentinaFil: Altcheh, Jaime Marcelo. Gobierno de la Ciudad de Buenos Aires. Hospital General de Niños "Ricardo Gutiérrez"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin