Weighted Approval Voting

To allow society to treat unequal alternatives distinctly we propose a natural extension of Approval Voting [7] by relaxing the assumption of neutrality. According to this extension, every alternative receives ex-ante a non-negative and finite weight. These weights may differ across alternatives. Given the voting decisions of every individual (individuals are allowed to vote for, or approve of, as many alternatives as they wish to), society elects all alternatives for which the product of total number of votes times exogenous weight is maximal. Our main result is an axiomatic characterization of this voting procedure.microeconomics ;

Incomplete Information and Small Cores in Matching Markets

We study Bayesian Nash equilibria of stable mechanisms in centralized matching markets under incomplete information. We show that truth-telling is a Bayesian Nash equilibrium of the revelation game induced by a common belief and a stable mechanism if and only if all the profiles in the support of the common belief have singleton cores. Our result matches the observations of Roth and Peranson (1999) in the National Resident Matching Program (NRMP) in the United States: (i) the cores of the profiles submitted to the clearinghouse are small and (ii) while truth-telling is not a dominant strategy most participants of the NRMP truthfully reveal their preferences.Matching Market, Incomplete Information, Small Core

Efficient and Stable Collective Choices under Gregarious Preferences

We consider collective choice problems where a set of agents have to choose an alternative from a finite set and agents may or may not become users of the chosen alternative. An allocation is a pair given by the chosen alternative and the set of its users. Agents have gregarious preferences over allocations: given an allocation, they prefer that the set of users becomes larger. We require that the final allocation be efficient and stable (no agent can be forced to be a user and no agent who wants to be a user can be excluded). We propose a two-stage sequential mechanism whose unique subgame perfect equilibrium outcome is an efficient and stable allocation which also satisfies a maximal participation property.Public Goods, Gregarious Preferences, Subgame Perfect Implementation

Efficient and Stable Collective Choices under Crowding Preferences

We consider a set of agents who have to choose one alternative among a finite set of social alternatives. A final allocation is a pair given by the selected alternative and the group of its users. Agents have crowding preferences over allocations: between any pair of allocations with the same alternative, they prefer the allocation with the largest number of users. We require that a decision be efficient and stable (which guarantees free participation in the group of users and free exit from it). We propose a two-stage sequential mechanism whose unique subgame perfect equilibrium outcome is an efficient and stable allocation which also satisfies a maximal participation property. The social choice function implemented by the proposed mechanism is also anonymous and group stable.Public Goods, Crowding Preferences, Subgame Perfect Implementation

Les aportacions de John F. Nash a l'economia : equilibri i negociació

John F. Nash va rebre el Premi Nobel d'Economia l'any 1994, juntament amb John C. Harsanyi i Reinhard Selten, «per les seves anàlisis de l'equilibri en la teoria dels jocs no cooperatius», i el Premi Abel de Matemàtiques l'any 2015, juntament amb Louis Nirenberg, «per les seves contribucions notables i fonamentals a la teoria d'equacions en derivades parcials no lineals i les seves aplicacions a l'anàlisi geomètrica». Aquest article presenta les dues contribucions més importants de Nash a l'economia: l'equilibri de Nash d'un joc no cooperatiu i la solució de Nash al problema de la negociació

The theory of stable allocations and the practice of market design. The Nobel Prize in Economics 2012 for Alvin E. Roth and Lloyd S. Shapley

Financial support received from the Spanish Ministry of Economy and Competitiveness, through the Severo Ochoa Programme for Centers of Excellence in R&D (SEV-2015-0563) and through grants ECO2008-0475-FED-ER (Grupo Consolidado-C) and ECO2014-53051, and from the Generalitat de Catalunya, through grant SGR2014-515.The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel 2012 was awarded jointly to Alvin E. Roth and Lloyd S. Shapley for their contributions to the theory of stable allocations and the practice of market design. The theory of stable allocations consists of a family of models that study assignment problems in which two disjoint sets of agents (or a set of agents and a set of objects) have to be matched. For example, men to women, workers to firms, students to schools, or patients to live donor kidneys. A matching is stable if no subset of agents can improved upon their proposed matches by rematching only among themselves. Stability is an essential property if matching is voluntary. The practice of market design consists of applying those two-sided matching models to specific assignment problems with the aim of proposing improvements on how they are solved. This paper presents a brief description of the academic career of the laureates and describes their contributions by presenting the most basic two-sided matching model and some of its market design applications, including the organization of a centralized system to propose kidney transplantations to use kidneys of live donors that are incompatible with their respective patients, the yearly assignment of North-American medical students to hospital internship programs, and children to schools in cities such as Boston and New York. [Contrib Sci 11(1): 103-112 (2015)

Entrevista a Antoni Muntadas

Antoni Muntadas (Barcelona, 1942) es una referencia en el videoarte internacional gracias a una extensa carrera, iniciada a finales de los años 60 del siglo XX. Pocos artistas como él han meditado acerca de la conexión entre lo sensorial y la tecnología, reflexión acompañada siempre por una acerada crítica de los medios de comunicación. En los trabajos de Muntadas, la agudización de los sentidos se antoja la única herramienta del receptor frente a los mecanismos de poder y a sus mensajes. Pero este Premio Nacional de Artes Plásticas en 2005 también ha considerado parte fundamental de su trabajo la docencia, impartida en instituciones como el MIT, en la que comparte con sus estudiantes lo que él denomina la “metodología del proyecto”. En esta entrevista, que coincidió con la amplia retrospectiva que el Museo Reina Sofía le dedicó en 2012, Muntadas repasa su trayectoria y explica la función que, según él, debe tener el artista como docente

Normalidad de la crisis, crisis de la normalidad

Reseña del libro: Cadahia, L., Velasco, G. (comp.). Normalidad de la crisis, crisis de la normalidad. Madrid: Katz, 201

The Multiple-partners Assignment Game with Heterogeneous Sells and Multi-unit Demands: Competitive Equilibria

A multiple-partners assignment game with heterogeneous sells and multi-unit demands consists of a set of sellers that own a given number of indivisible units of (potentially many different) goods and a set of buyers who value those units and want to buy at most an exogenously fixed number of units. We define a competitive equilibrium for this generalized assignment game and prove its existence by only using linear programming. We show that the set of competitive equilibria (pairs of price vectors and assignments) has a Cartesian product structure: each equilibrium price vector is part of a competitive equilibrium with all equilibrium assignments, and vice versa. We also show that the set of (restricted) equilibrium price vectors has a natural lattice structure and we study how this structure is translated into the set of agents' utilities that are attainable at equilibrium.Matching, Assignment Game, Indivisible Goods, Competitive Equilibrium, Lattice