Invoking a cartesian product structure on social states: new resolutions of Sen's and Gibbard's impossibility theorems

The purpose of this article is to introduce a Cartesian product structure into the social choice theoretical framework and to examine if new possibility results to Gibbard's and Sen's paradoxes can be developed thanks to it. We believe that a Cartesian product structure is a pertinent way to describe individual rights in the social choice theory since it discriminates the personal features comprised in each social state. First we define some conceptual and formal tools related to the Cartesian product structure. We then apply these notions to Gibbard's paradox and to Sen's impossibility of a Paretian liberal. Finally we compare the advantages of our approach to other solutions proposed in the literature for both impossibility theorems.

Interactions between product and labour market reforms

Labour market reforms face very often opposition from the employed workers, because it normally reduces their wages. Also product market regulations are regularly biased towards too much benefitting the firms. As a result there remain many frictions in both the labour and product markets that hinder an optimal functioning of the economy. These issues have recently received a lot of attention in the economics literature and scholars have been looking for politically viable reforms in both markets. However, despite its potential importance, there has been done virtually no research on the interaction between reforms in product and labour markets. We find that when combining reforms, the opposition for reforms decreases considerably. This is because there exist complementarities and the gains in total welfare can be more evenly distributed over the interest groups. Moreover, the interaction of reforms offers a way out for the so-called 'sclerosis' effect.

Multi-product firms and product variety

The goal of this paper is to study the role of multi-product firms in the market provision of product variety. The analysis is conducted using the spokes model of non-localized competition proposed by Chen and Riordan (2007). Firstly, we show that multi-product firms are at a competitive disadvantage vis-a-vis single-product firms and can only emerge if economies of scope are sufficiently strong. Secondly, under duopoly product variety may be higher or lower with respect to both the first best and the monopolistically competitive equilibrium. However, within a relevant range of parameter values duopolists drastically restrict their product range in order to relax price competition, and as a result product variety is far below the efficient level.

RADIC II: a fault tolerant architecture with flexible dynamic redundancy

The demand for computational power has been leading the improvement of the High Performance Computing (HPC) area, generally represented by the use of distributed systems like clusters of computers running parallel applications. In this area, fault tolerance plays an important role in order to provide high availability isolating the application from the faults effects. Performance and availability form an undissociable binomial for some kind of applications. Therefore, the fault tolerant solutions must take into consideration these two constraints when it has been designed. In this dissertation, we present a few side-effects that some fault tolerant solutions may presents when recovering a failed process. These effects may causes degradation of the system, affecting mainly the overall performance and availability. We introduce RADIC-II, a fault tolerant architecture for message passing based on RADIC (Redundant Array of Distributed Independent Fault Tolerance Controllers) architecture. RADIC-II keeps as maximum as possible the RADIC features of transparency, decentralization, flexibility and scalability, incorporating a flexible dynamic redundancy feature, allowing to mitigate or to avoid some recovery side-effects.

System analysis of a Peer-to-Peer Video-on-Demand architecture: Kangaroo

Architectural design and deployment of Peer-to-Peer Video-on-Demand (P2PVoD) systems which support VCR functionalities is attracting the interest of an increasing number of research groups within the scientific community; especially due to the intrinsic characteristics of such systems and the benefits that peers could provide at reducing the server load. This work focuses on the performance analysis of a P2P-VoD system considering user behaviors obtained from real traces together with other synthetic user patterns. The experiments performed show that it is feasible to achieve a performance close to the best possible. Future work will consider monitoring the physical characteristics of the network in order to improve the design of different aspects of a VoD system.

A functional equation related to the product in a quadratic number field

"Vegeu el resum a l'inici del document del fitxer adjunt."

Product differentiation, competitive pressure and the effects of innovation on the success and survivability of firms in oligopoly markets

In a recent paper Tishler and Milstein (2009) fi…nd that increased competition may increase aggregate R&D spending while market output decreases. Therefore, they obtain the surprising result that R&D spending is excessive when competition becomes intense. Their result is based on the standard linear demand function for differentiated products introduced by Bowley (1924) where decreased product differentiation is interpreted as more competitive pressure. In this paper I show that at an aggregate level this interpretation is problematic because equilibrium effects are dominated by a demand reduction effect. A slight modifi…cation of the standard demand function eliminates this effect. For the Tishler and Milstein (2009) setting it is shown that then increased competition increases both R&D spending and aggregate market output. Therefore, at least for consumers, more intense competition increases welfare. Journal of Economic Literature Classi…fication Numbers: D43, L1, O3. Keywords: Oligopoly markets, Product differentiation, Competitive pressure.

Profitability, uncertainty and multi-product firm product proliferation: The Spanish car industry

This article studies how product introduction decisions relate to profitability and uncertainty in the context of multi-product firms and product differentiation. These two features, common to many modern industries, have not received much attention in the literature as compared to the classical problem of firm entry, even if the determinants of firm and product entry are quite different. The theoretical predictions about the sign of the impact of uncertainty on product entry are not conclusive. Therefore, an econometric model relating firms’ product introduction decisions with profitability and profit uncertainty is proposed. Firm’s estimated profits are obtained from a structural model of product demand and supply, and uncertainty is proxied by profits’ variance. The empirical analysis is carried out using data on the Spanish car industry for the period 1990-2000. The results show a positive relationship between product introduction and profitability, and a negative one with respect to profit variability. Interestingly, the degree of uncertainty appears to be a driving force of entry stronger than profitability, suggesting that the product proliferation process in the Spanish car market may have been mainly a consequence of lower uncertainty rather than the result of having a more profitable market. Keywords: Product introduction, entry, uncertainty, multiproduct firms, automobile JEL codes: L11, L13

Dynamic product diversity

The goal of this paper is to study the frequency of new product introductions in monopoly markets where demand is subject to transitory saturation. We focus on those types of goods for which consumers purchase at most one unit of each variety, but repeat purchases in the same product category. The model considers infinitely-lived, forward-looking consumers and firms. We show that the share of potential surplus that a monopolist is able to appropriate increases with the frequency of introduction of new products and the intensity of transitory saturation. If the latter is sufficiently strong then the rate of introduction of new products is higher than socially desirable (excessive dynamic product diversity.)

Sistemes de pagament

Al llarg d'aquest treball es desenvolupa un sistema de micropagament basat en un model client - servidor en què el procés d'intercanvi de dades no necessita ser validat en temps real. El client té una cartera on guarda les monedes de què disposa per a fer les compres, i el servidor demana les monedes abans de fer la transferència del producte adquirit; aquestes monedes són guardades pel servidor i al final del dia es fa la conversió a diners.

Catalogo.NET Sistema multicliente con arquitectura SOA basado en tecnología .NET

El paradigma SOA conceptualitza el programari establint una separació entre les aplicacions i els components de lògica empresarial. El present Treball de Fi de Carrera uneix ambdós conceptes mitjançant l'anàlisi, disseny i desenvolupament d'un Catàleg de Productes amb Arquitectura Orientada a Serveis i tecnologia .NET com marc de treball. Així mateix, s'han introduït com valor afegit una sèrie de tecnologies noves que contribuïxen, sens dubte, a la millora del resultat final.

J2EE : gestió d'una xarxa de biblioteques

Desenvolupament d'un producte complet utilitzant la tecnologia proporcionada per la plataforma J2EE passant per les etapes d'anàlisi, disseny i implementació. El tema escollit ha estat l'aplicació web per la gestió d'una xarxa de biblioteques (consulta del catàleg de llibres disponibles i gestió de préstecs). L'aplicació es desenvolupa seguint els estàndards actuals de l'enginyeria del programari i amb les eines proporcionades per la plataforma J2EE. S'han utilitzat els frameworks Hibernate i Struts seguint els patrons d'arquitectura MVC.

VLSI architecture for an Underwater Robot Vision System

It is well known that image processing requires a huge amount of computation, mainly at low level processing where the algorithms are dealing with a great number of data-pixel. One of the solutions to estimate motions involves detection of the correspondences between two images. For normalised correlation criteria, previous experiments shown that the result is not altered in presence of nonuniform illumination. Usually, hardware for motion estimation has been limited to simple correlation criteria. The main goal of this paper is to propose a VLSI architecture for motion estimation using a matching criteria more complex than Sum of Absolute Differences (SAD) criteria. Today hardware devices provide many facilities for the integration of more and more complex designs as well as the possibility to easily communicate with general purpose processors

Proposal of a parallel architecture for a motion detection algorithm

This paper proposes a parallel architecture for estimation of the motion of an underwater robot. It is well known that image processing requires a huge amount of computation, mainly at low-level processing where the algorithms are dealing with a great number of data. In a motion estimation algorithm, correspondences between two images have to be solved at the low level. In the underwater imaging, normalised correlation can be a solution in the presence of non-uniform illumination. Due to its regular processing scheme, parallel implementation of the correspondence problem can be an adequate approach to reduce the computation time. Taking into consideration the complexity of the normalised correlation criteria, a new approach using parallel organisation of every processor from the architecture is proposed

On AUV control architecture

This paper surveys control architectures proposed in the literature and describes a control architecture that is being developed for a semi-autonomous underwater vehicle for intervention missions (SAUVIM) at the University of Hawaii. Conceived as hybrid, this architecture has been organized in three layers: planning, control and execution. The mission is planned with a sequence of subgoals. Each subgoal has a related task supervisor responsible for arranging a set of pre-programmed task modules in order to achieve the subgoal. Task modules are the key concept of the architecture. They are the main building blocks and can be dynamically re-arranged by the task supervisor. In our architecture, deliberation takes place at the planning layer while reaction is dealt through the parallel execution of the task modules. Hence, the system presents both a hierarchical and an heterarchical decomposition, being able to show a predictable response while keeping rapid reactivity to the dynamic environment