On the Properties of General Equilibrium with Default in Economies with Incomplete Markets

In this paper we study the properties of general equilibrium with default in economies with incomplete markets. It is noted that, in equilibrium, an agent makes two types of comparisons when deciding whether to participate in the credit market: as a lender and as a borrower. As a consequence, the equilibrium can be linked to levels of punishment, perception of default and promised returns. An analysis of equilibrium in the case of economies with two homogeneous types of agents is also presented, from which it can be deduced that in equilibrium under partial default the personal valuations of default for the buyer and the seller are equal.General equilibrium, incomplete markets, default

Picturesque Violence: Tourism, the Film Industry, and the Heritagization of ‘Bandoleros’ in Spain, 1905–1936

This article examines the debates about the Andalusian ‘bandoleros’ (bandits) in the context of early tourism as a state-guided policy in Spain. As we argue, the development of tourism made Spanish intellectuals reconsider the real armed activity in Andalucía as part of Spanish national heritage and a tourist attraction. Consistent with the stereotypical image of Spain coined by the Romantic travelers, such an early heritagization of brigandry reveals the role of the élites in recasting exotic imagery into modern tourism-shaped identities: in the hands of early century writers, bandits were reshaped as part of the ‘modern picturesque’. Furthermore, the role given to brigands in early cinema allows one to see how the early heritage discourse bridged transnational and centralist interests at the expense of the regional ones, thus foreshadowing the debates about hegemony in present-day heritage studies

Dirac Matrices for Chern-Simons Gravity

A genuine gauge theory for the Poincar\'e, de Sitter or anti-de Sitter algebras can be constructed in (2n-1)-dimensional spacetime by means of the Chern-Simons form, yielding a gravitational theory that differs from General Relativity but shares many of its properties, such as second order field equations for the metric. The particular form of the Lagrangian is determined by a rank n, symmetric tensor invariant under the relevant algebra. In practice, the calculation of this invariant tensor can be reduced to the computation of the trace of the symmetrized product of n Dirac Gamma matrices \Gamma_{ab} in 2n-dimensional spacetime. While straightforward in principle, this calculation can become extremely cumbersome in practice. For large enough n, existing computer algebra packages take an inordinate long time to produce the answer or plainly fail having used up all available memory. In this talk we show that the general formula for the trace of the symmetrized product of 2n Gamma matrices \Gamma_{ab} can be written as a certain sum over the integer partitions s of n, with every term being multiplied by a numerical coefficient \alpha_{s}. We then give a general algorithm that computes the \alpha-coefficients as the solution of a linear system of equations generated by evaluating the general formula for different sets of tensors B^{ab} with random numerical entries. A recurrence relation between different coefficients is shown to hold and is used in a second, "minimal" algorithm to greatly speed up the computations. Runtime of the minimal algorithm stays below 1 min on a typical desktop computer for up to n=25, which easily covers all foreseeable applications of the trace formula.Comment: v2: 6 pages, no figures. Based on talk presented at I Cosmosul, Rio de Janeiro, Brazil, August 2011. v3: references adde

Pigou’s Dividend versus Ramsey’s Dividend in the Double Dividend Literature

This paper deals with the welfare analysis of green tax reforms. The aims of this paper are to highlight misinterpretations of policy assessments in the double dividend literature, to specify which of the efficiency costs and benefits should be ascribed to each dividend, and then, to propose a definition for the first dividend and the second dividend. We found the Pigou’s dividend more appropriate for policy guidance, in contrast to the Ramsey’s dividend usually found in mainstream literature. Therefore, we take up some authors’ recent claims about the need of unambiguous and operative definitions of these dividends both for empirical purposes, and political advice. Finally, the paper analyzes a green tax reform for the US economy to illustrate the advantages of our definitions for policy assessment. The new definitions proposed in this paper i) overcome some shortcoming of the mainstream current definitions in the literature regarding overestimation of the efficiency costs; and, ii) provide information by themselves and not as a partial view of the whole picture.Double Dividend, Green Tax Reforms, Ramsey’s Dividend, Pigou’s Dividend

Computationally efficient min-max MPC

2005 IFAC 16th Triennial World Congress, Prague, Czech RepublicMin-Max MPC (MMMPC) controllers (Campo and Morari, 1987) suffer from a great computational burden that is often circumvented by using upper bounds of the worst possible case of a performance index. These upper bounds are usually computed by means of LMI techniques. In this paper a more efficient approach is shown. This paper proposes a computationally efficient MMMPC control strategy in which the worst case cost is approximated by an upper bound which can be easily computed using simple matrix operations. This implies that the algorithm can be coded easily even in non mathematical oriented programming languages such as those found in industrial embedded control hardware. Simulation examples are given in the paper

Computational burden reduction in Min-Max MPC

Min–max model predictive control (MMMPC) is one of the strategies used to control plants subject to bounded uncertainties. The implementation of MMMPC suffers a large computational burden due to the complex numerical optimization problem that has to be solved at every sampling time. This paper shows how to overcome this by transforming the original problem into a reduced min–max problem whose solution is much simpler. In this way, the range of processes to which MMMPC can be applied is considerably broadened. Proofs based on the properties of the cost function and simulation examples are given in the paper