'Genealogical misfortunes': Achille Mbembe's (re-)writing of postcolonial Africa

In his latest work, Sortir de la grande nuit, the Cameroonian social theorist, Achille Mbembe nuances his description of the ontological status of the postcolonial African subject, which he had theorized extensively in his best-known text, On the Postcolony, and at the same time exploits the conceptual resources of a number of Jean-Luc Nancy’s lexical innovations. This recent text is also a reprise of an earlier autobiographical essay, and the gesture of this ‘reinscription’ is critical to our understanding of Mbembe’s status as a contemporary ‘postcolonial thinker’, and the way in which he positions himself within a certain intellectual genealogy of postcolonial theory. Within this trajectory, I argue that we can read fruitfully his relationship to three influential figures: Jacques Derrida, Jean-Luc Nancy and Ruben Um Nyobè

Optimal Trading Mechanisms with Ex Ante Unidentified Traders

We analyze optimal trading mechanisms in an exchange economy where each trader owns some units of a good to be traded and may be either a seller or a buyer, depending on the realization of the privately observed valuations. The concept of virtual valuation is extended to ex ante unidentified traders; contrary to the case where each trader is assigned a role as either a buyer or a seller, the traders' virtual valuations now depend on the choice of the trading mechanism and are generally non-monotonic even if the distribution of valuations is regular. We show that the trading mechanisms that maximize a broker's expected profit or expected total gains from trade are generalized double auctions which maximize the gains from trade measured in some modified monotonic virtual valuations for the traders. The bunching phenomena, which are here specific to ex ante unidentified traders, will be a general feature in these mechanisms. Furthermore, the randomization rule by which ties are broken is now part of the design of the optimal mechanisms. Finally, we show that the optimal mechanism converges toward a simple bid-ask mechanism as the number of participants in the market increases.

The Economics of Free and Open Source Software: Contributions to a Government Policy on Open Source Software

This document seeks to lay the groundwork for a government policy on free and open source software. We briefly characterize the extent of the open source software phenomenon. We analyse its pros and cons for the government, in its role as both an engine of economic development and a large user of information and communications technologies. We conclude with a series of recommendations for the government, as both “economic and industrial policy maker” and “large user.”free software, intellectual property rights, free source code, open source code, free operating system, GPL licence, BSD licence, innovation, forking,

Implementing the Optimal Auction

In a general framework with independent private values of the bidders, we propose a game, with a simple economic interpretation, that allows implementing the optimal auction outcome when the seller ignores the distributions of the different bidders' valuations. In this robust or detail-free implementation procedure, a second-price auction is organized and the winner volunteers a payment to the seller; this payment can then be challenged by another bidder who knows the distribution of the winner's valuation. Dans un cadre du modèle d'enchères avec des valeurs privées indépendantes, nous proposons un jeu, ayant une interprétation économique simple, qui permet de mettre en oeuvre les enchères optimales même quand le vendeur ignore les distributions des volontés à payer des différents soumissionnaires. Dans cette procédure robuste (detail-free), une enchère au deuxième prix est organisée et le gagnant de cette enchère propose un paiement au vendeur; ce paiement peut alors être contesté par un autre soumissionnaire qui connaît la distribution de l'évaluation du gagnant.Auction, mechanism design, Wilson doctrine, Enchères, design de mécanismes, doctrine de Wilson

Reduced-order 4D-Var: a preconditioner for the Incremental 4D-Var data assimilation method

This study demonstrates how the incremental 4D-Var data assimilation method can be applied efficiently preconditione d in an application to an oceanographic problem. The approach consists in performing a few iterations of the reduced-order 4D-Var prior to the incremental 4D-Var in the full space in order to achieve faster convergence. An application performed in the tropical Pacific Ocean, with assimilation of TAO temperature data, shows the method to be both feasible and efficient. It allows the global cost of the assimilation to be reduced by a factor of 2 without affecting the quality of the solution

Ex Ante Incentives and Ex Post Flexibility

Our objective in this paper is to illustrate and better understand the unavoidable arbitrage between incentives and flexibility in contexts of asymmetric information and to characterize the general features of an appropriate response to this challenge. We show that procedures and institutions in organizations which reduce the capacity to implement change may be necessary to generate the optimal level of inertia. We show that more flexibility in adapting to changing conditions or new information, typically known or observed by either the agent or the principal but not both, may come at the expense of efforts exerted up front by the agent to make the organization more successful. There is a trade-off in this context between ex ante efforts and ex post flexibility of adaptation. Nous développons dans cet article un modèle principal-agent permettant de mieux cerner l'arbitrage inéluctable entre incitations et flexibilité en situation d'information asymétrique. Nous caractérisons la meilleure réponse de l'organisation face à ce défi en termes d'un niveau optimal d'inertie. Une plus grande flexibilité d'adaptation aux changements dans l'environnement ou l'information, que ces changements soient observés par le principal ou l'agent, peut réduire les efforts non-observables consentis par l'agent pour assurer le succès de l'organisation.Incentives, Flexibility, Adaptation, Asymmetric Information, Incitations, Flexibilité, Adaptation, Information asymétrique

Consumer Search and Information Intermediaries

In this paper we model the market for a homogeneous good and examine the role of information in determining market outcomes. Unlike in Baye and Morgan (2001) where consumers can only learn about the prices charged by different firms by subscribing to an information intermediary’s service, we allow consumers to shop for price quotes. We are interested in determing the impact on market outcomes of allowing for this additional means of information acquisition. Relative to the case where consumers have no interest in searching for prices, consumers become no better off as the cost of search falls. The intermediary, in an effort to compensate for the loss of revenue that it might have earned from consumers, increases the fees that it charges to firms for the right to advertise their product through it. As a result, fewer firms advertise in equilibrium, and so, those that do post higher prices, and, in expectation, consumers pay more for the product. The price increase appropriates all of the gains in consumer surplus generated by the decrease in the cost of search.Search, advertising, information intermediary, price dispersion

Comparison of reduced-order, sequential and variational data assimilation methods in the tropical Pacific Ocean

This paper presents a comparison of two reduced-order, sequential and variational data assimilation methods: the SEEK filter and the R-4D-Var. A hybridization of the two, combining the variational framework and the sequential evolution of covariance matrices, is also preliminarily investigated and assessed in the same experimental conditions. The comparison is performed using the twin-experiment approach on a model of the Tropical Pacific domain. The assimilated data are simulated temperature profiles at the locations of the TAO/TRITON array moorings. It is shown that, in a quasi-linear regime, both methods produce similarly good results. However the hybrid approach provides slightly better results and thus appears as potentially fruitful. In a more non-linear regime, when Tropical Instability Waves develop, the global nature of the variational approach helps control model dynamics better than the sequential approach of the SEEK filter. This aspect is probably enhanced by the context of the experiments in that there is a limited amount of assimilated data and no model error

GPS vertical axis performance enhancement for helicopter precision landing approach

Several areas were investigated for improving vertical accuracy for a rotorcraft using the differential Global Positioning System (GPS) during a landing approach. Continuous deltaranging was studied and the potential improvement achieved by estimating acceleration was studied by comparing the performance on a constant acceleration turn and a rough landing profile of several filters: a position-velocity (PV) filter, a position-velocity-constant acceleration (PVAC) filter, and a position-velocity-turning acceleration (PVAT) filter. In overall statistics, the PVAC filter was found to be most efficient with the more complex PVAT performing equally well. Vertical performance was not significantly different among the filters. Satellite selection algorithms based on vertical errors only (vertical dilution of precision or VDOP) and even-weighted cross-track and vertical errors (XVDOP) were tested. The inclusion of an altimeter was studied by modifying the PVAC filter to include a baro bias estimate. Improved vertical accuracy during degraded DOP conditions resulted. Flight test results for raw differential results excluding filter effects indicated that the differential performance significantly improved overall navigation accuracy. A landing glidepath steering algorithm was devised which exploits the flexibility of GPS in determining precise relative position. A method for propagating the steering command over the GPS update interval was implemented

Exploring the issues in knowledge management

This paper introduces a general, formal treatment of dynamic constraints, i.e., constraints on the state changes that are allowed in a given state space. Such dynamic constraints can be seen as representations of "real world" constraints in a managerial context. The notions of transition, reversible and irreversible transition, and transition relation will be introduced. The link with Kripke models (for modal logics) is also made explicit. Several (subtle) examples of dynamic constraints will be given. Some important classes of dynamic constraints in a database context will be identified, e.g. various forms of cumulativity, non-decreasing values, constraints on initial and final values, life cycles, changing life cycles, and transition and constant dependencies. Several properties of these dependencies will be treated. For instance, it turns out that functional dependencies can be considered as "degenerated" transition dependencies. Also, the distinction between primary keys and alternate keys is reexamined, from a dynamic point of view.