Consider a general equilibrium framework where the marginal cost of extraction from several deposits of an exhaustible resource is constant in terms of an inexhaustible perfect substitute and differs between deposits. The instantaneous rate of production from the inexhaustible resource is subject to a capacity constraint. We show, under standard assumptions, that not only may it be optimal to begin using a high cost resource before a lower cost one is depleted, as shown in Kemp and Long (1980a), but it may be optimal to begin using it strictly before the lower cost one is even put into use. Thus the intuitive principle, derived from partial equilibrium analysis, that when the rate of discount is positive natural resources should always be exploited in strictly increasing order of costs, not only does not hold in a general equilibrium context, but may be totally reversed.

Objective This article aims at explaining national medal totals at the 1992–2016 Summer Olympic Games (n = 1,289 observations) and forecasting them in 2016 (based on 1992–2012 data) and 2020 with a set of variables similar to previous studies, as well as a regional (subcontinents) variable not tested previously in the literature in English. Method Econometric testing not only resorts to a Tobit model as usual but also to a Hurdle model. Results Most variables have a significant impact on national team medal totals; it appears to be negative for most regions other than North America except Western Europe and Oceania (not significant). Then, two models (Tobit and Hurdle) are implemented to forecast national medal totals at the 2016 and 2020 Summer Olympics. Conclusion Both models are complementary for the 2016 forecast. The 2020 forecast is consistent with Olympic Medals Predictions, although some striking differences are found.

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This paper examines the link between pollution and income. The main purpose is to assess whether the introduction of income inequality in a Environmental Kuznets Curve (EKC) analysis can give new insights into the relationship between pollution and economic growth. The EKC hypothesis proposes that there is an inverted U-shape relation between environmental degradation and income per capita. We question this common result, in a simple model where the income inequality evolution is exogenous and where the planner could use only one instrument. For a set of parameter values we find, for example, a two-hump curve. JEL classification: D3, H4, Q2.Est-ce que le postulat de S. Kuznets remet en question les courbes environnementales a`la Kuznets? Cet article analyse la relation entre pollution et revenu. L'objectif de cet article est de montrer comment la prise en compte de l'ine´galite´des revenus, dans une analyse de la courbe environnementale de Kuznets, peut modifier la relation entre pollution et croissance. L'hypothe`se de la courbe environnementale de Kuznets revient a`supposer l'existence d'une forme en U inverse´entre la de´gradation de l'environnement et le revenu par teˆte. Cet article remet en cause ce re´sultat a`l'aide d'un mode`le simple dans lequel l'ine´galite´du revenu e´volue de manie`re exoge`ne et ou`le planificateur ne peut utiliser qu'un seul instrument. Pour certaines valeurs des parame`tres du mode`le nous trouvons que la relation entre la pollution et le revenu suit une courbe a`deux bosses.

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