Constraining inverse-curvature gravity with supernovae

We show that models of generalized modified gravity, with inverse powers of the curvature, can explain the current accelerated expansion of the Universe without resorting to dark energy and without conflicting with solar system experiments. We have solved the Friedmann equations for the full dynamical range of the evolution of the Universe and performed a detailed analysis of supernovae data in the context of such models that results in an excellent fit. If we further include constraints on the current expansion of the Universe and on its age, we obtain that the matter content of the Universe is 0.07 <=omega(m)<= 0.21 (95% C.L.). Hence the inverse-curvature gravity models considered cannot explain the dynamics of the Universe just with a baryonic matter component

TARIFF AGREEMENTS AND NON-RENEWABLE RESOURCE INTERNATIONAL MONOPOLIES: PRICES VERSUS QUANTITITES

In this paper we model the case of an international non-renewable resource monopolist as a differential game between the monopolist and the governments of the importing countries, and we investigate whether a tariff on the resource importations can be advantageous for the importing countries. We find that the results depend crucially on the kind of strategies the importing country governments can play and on whether the monopolist chooses the price or the extraction rate. For a price-setting monopolist it is shown that the importing countries cannot use a tariff to capture monopoly rents if they are constrained to use open-loop strategies, even if the governments sign a tariff agreement. This result is drastically modified if the importing countries in the tariff agreement use Markov (feedback) strategies. For a quantity-setting monopolist the nature of the game changes and an open-loop tariff is advantageous for the importing countries. Moreover, in this case the importing countries in a tariff agreement enjoy a strategic advantage which allows them to behave as a leader.tariffs, tariff agreements, non-renewable resources, depletion effects, price-setting monopolist, quantity-setting monopolist, differential games, open-loop strategies, linear strategies, Markov-perfect Nash equilibrium, Markov-perfect Stackelberg equilibrium

On the Coincidence of the Feedback Nash and Stackelberg Equilibria in Economic Applications of Differential Games

In this paper the scope of the applicability of the Stackelberg equilibrium concept in differential games is investigated. Firstly, conditions for obtaining the coincidence between the Stackelberg and Nash equilibria are defined in terms of the instantaneous pay-off function and the state equation of the game. Secondly, it is showed that for a class of differential games with state-interdependence both equilibria are identical independently of the player being the leader of the game. A survey of different economic models shows that this coincidence is going to occur for a good number of economic applications of differential games. This result appears because of the continuous-time setting in which differential games are defined. In this setting the first movement advantage of the leader may disappear and the both equilibria coincide.Differential games, stationary feedback Nash equilibrium, stationary feedback Stackelberg equilibrium.

On Capturing Oil Rents with a National Excise Tax Revisited

In this paper the scope of Bergstrom’s (1982) results is studied. Moreover, his analysis is extended assuming that extraction cost is directly related to accumulated extractions. For the case of a competitive market it is found that the optimal policy is a constant tariff if extraction is costless. However, with depletion effects, the optimal tariff must ultimately be decreasing. For the case of a monopolistic market the results depend crucially on the kind of strategies the importing country governments can play and on whether the monopolist chooses the price or extraction rate. For a price-setting monopolist it is shown that the importing countries cannot use a tariff to capture monopoly rents if they are constrained to use open-loop strategies, even if the governments sign a tariff agreement. This result is drastically modified if the importing countries in the tariff agreement use Markov (feedback) strategies. For a quantity-setting monopolist the nature of the game changes and the importing country governments find it advantageous to set a tariff on resource importations. Moreover, in this case the importing countries in a tariff agreement enjoy a strategic advantage which allows them to behave as a leader.Tariffs, Tariff agreements, Non renewable resources, Depletion effects, Price-setting monopolist, Quantity-setting monopolist, Differential games, Open-loop strategies, Linear strategies, Markov-perfect Nash equilibrium, Markov-perfect Stackelberg equilibrium

ON THE COINCIDENCE OF THE FEEDBACK NASH AND STACKELBERG EQUILIBRIA IN ECONOMIC APPLICATIONS OF DIFFERENTIAL GAMES

In this paper the scope of the applicability of the Stackelberg equilibrium concept in differential games is investigated. Firstly, it is showed that for a class of differential games with state-interdependence the stationary feedback Nash equilibrium coincides with the stationary feedback Stackelberg equilibrium independently of the player being the leader of the game. Secondly, sufficient conditions for obtaining the coincidence between the two equilibria are defined. A review of different economic models shows that this coincidence is going to occur for a good number of economic applications of differential games. This result appears because of the continuous-time setting in which differential games are defined. In this setting the first movement advantage of the leader may disappears and then both equilibria coincide.Differential Games; Stationary Feedback Nash Equilibrium; Stationary Feedback Stackelberg Equilibrium; Coincidence.

Secondary Effects and Public Morality

The police power consists of the authority of the state to regulate in the interests of public health, safety, and morals. As American society continues to grow more diverse and pluralistic, courts and commentators have raised concerns that the last of these, public morality, cannot serve as an acceptable justification for regulatory action. Indeed, if appeals to public morality cannot be evaluated on an objective basis, then regulators might invoke them to conceal unlawful motives. The ability of moral reasoning to provide a legitimate basis for regulation is thrown into doubt. In this Article, we examine a peculiar line of Supreme Court cases in the free speech context that bring the problem into focus. In the so-called secondary effects cases, the Justices gradually moved away from accepting public morality arguments in support of state restrictions on adult businesses. In place of public morality, the Court began to retrain its focus on the social ills attendant to the activity in question, or what it termed the ?secondary effects? of such conduct. Rather than decide whether the regulated activity is immoral, and thus within the legitimate regulatory sweep of the police power as traditionally conceived, the Court instead looked to whether the state could show that its restriction reduced deleterious secondary effects associated with the activity. This development might have appeared desirable insofar as it would permit courts to rest their rulings on objective facts rather than wrestle with matters of opinion and moral sentiment. To the contrary, we argue, secondary effects arguments rely on moral reasoning –whether articulated or not– to the same extent as public morality arguments. The Court?s attempt in the secondary effects cases to avoid engaging in moral reasoning in reality demonstrates its indispensability.Fil: Legarre, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Notre Dame-Indiana; Estados Unidos. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; ArgentinaFil: Mitchell, Gregory J. Notre Dame Law School; Estados Unido