On the exhaustiveness of truncation and dropping strategies in many-to-many matching markets

We consider two–sided many–to–many matching markets in which each worker may work for multiple firms and each firm may hire multiple workers. We study individual and group manipulations in centralized markets that employ (pairwise) stable mechanisms and that require participants to submit rank order lists of agents on the other side of the market. We are interested in simple preference manipulations that have been reported and studied in empirical and theoretical work: truncation strategies, which are the lists obtained by removing a tail of least preferred partners from a preference list, and the more general dropping strategies, which are the lists obtained by only removing partners from a preference list (i.e., no reshuffling). We study when truncation / dropping strategies are exhaustive for a group of agents on the same side of the market, i.e., when each match resulting from preference manipulations can be replicated or improved upon by some truncation / dropping strategies. We prove that for each stable mechanism, truncation strategies are exhaustive for each agent with quota 1 (Theorem 1). We show that this result cannot be extended neither to group manipulations (even when all quotas equal 1 – Example 1), nor to individual manipulations when the agent’s quota is larger than 1 (even when all other agents’ quotas equal 1 – Example 2). Finally, we prove that for each stable mechanism, dropping strategies are exhaustive for each group of agents on the same side of the market (Theorem 2), i.e., independently of the quotas.

Contratación atípica en el sector central de la administración pública colombiana (ministerios y departamentos administrativos)

El Estatuto General de Contratación colombiano (Ley 80 de 1993 y normas que lo aclaran, complementan y desarrollan), como desarrollo de los artículos 4 y 209 de la Constitución Política y como ejemplo de la implantación de nuevas maneras de entender el derecho administrativo, habilita a las entidades estatales sujetas al estatuto general de contratación, en aras de alcanzar sus fines constitucionales y legales, para acudir a contratos del derecho privado, plasmados en normas especiales y aquellos derivados del ejercicio de la autonomía de la voluntad, sin que ello se oponga al principio de legalidad, piedra angular del derecho público. No obstante esta autorización legal expresa, el uso de contratos atípicos es muy limitado.

Quantil Hedging for telegraph markets and its applications to a pricing of equity-linked life insurance contracts

En este documento está desarrollado un modelo de mercado financiero basado en movimientos aleatorios con tiempo continuo, con velocidades constantes alternantes y saltos cuando hay cambios en la velocidad. Si los saltos en la dirección tienen correspondencia con la dirección de la velocidad del comportamiento aleatorio subyacente, con respecto a la tasa de interés, el modelo no presenta arbitraje y es completo. Se construye en detalle las estrategias replicables para opciones, y se obtiene una presentación cerrada para el precio de las opciones. Las estrategias de cubrimiento quantile para opciones son construidas. Esta metodología es aplicada al control de riesgo y fijación de precios de instrumentos de seguros.

Do more decentralized local governments do better? an evaluation of the 2001 decentralization reform in Colombia

In this paper I evaluate the impact of the 2001 decentralization reform in Colombia. I use data from Colombia's municipalities. I look at the effect of the 2001 reform on enrolment in pre-college schools. While all municipalities received earnmarked national transfers, withthe reform some of then now have more responsabilities to provide education (deeper decen-tralization) than others. Particulary important, the reform entitle the more decentralizedmunicipalities to sign subsidy contracts with private school. Departments (the regional gov-ernments) are entitle to sign this type of contracts for the less decentralized municipalities.Since the rule for municipalities to receive more responsabilities follows and exogenous popu-lation threshold, I can implement Regression Discontinuity Design. Enrolment is measuredthrough two variables: the number of students enroled in public schools and the number of subsidized students enroled in private schools. Results sugest that more decentralized mu-nicipalities subsidize more students in private schools. The difference is significant at all thelevels of pre-college school for the period 2004-2006. In 2005, the difference accounts for20% of enrolment in private schools and 3% of population of school age. Besides, there are not significant differences among municipalities regarding enrolment in public schools.