Avaluació de l'estàndard SQL : 1999 respecte les característiques orientades a l'objecte que suporta i la seva implementació als SGBD object-relational

L'objectiu és estudiar les característiques orientades a l'objecte de l'estàndard SQL: 1999 i posar-les a prova amb un producte comercial que les suporti.

A Homogeneous Set-Theoretical Frame for Clustering Fuzzy Relational Data

Our purpose is to provide a set-theoretical frame to clustering fuzzy relational data basically based on cardinality of the fuzzy subsets that represent objects and their complementaries, without applying any crisp property. From this perspective we define a family of fuzzy similarity indexes which includes a set of fuzzy indexes introduced by Tolias et al, and we analyze under which conditions it is defined a fuzzy proximity relation. Following an original idea due to S. Miyamoto we evaluate the similarity between objects and features by means the same mathematical procedure. Joining these concepts and methods we establish an algorithm to clustering fuzzy relational data. Finally, we present an example to make clear all the process

An automatic correction tool for relational database schemas

A Web-based tool developed to automatically correct relational database schemas is presented. This tool has been integrated into a more general e-learning platform and is used to reinforce teaching and learning on database courses. This platform assigns to each student a set of database problems selected from a common repository. The student has to design a relational database schema and enter it into the system through a user friendly interface specifically designed for it. The correction tool corrects the design and shows detected errors. The student has the chance to correct them and send a new solution. These steps can be repeated as many times as required until a correct solution is obtained. Currently, this system is being used in different introductory database courses at the University of Girona with very promising results

Determinants of acquisition completion: a relational perspective

The strategic literature on relatedness in the context of mergers and acquisitions (M&As) is extensive, yet we know little about whether or how relatedness has an influence on the announcement to completion stage of the M&A process. Drawing on research on intra-industry competition and relational capabilities, we seek to shed light on the relatedness debate by examining the strategic forces that affect the completion of an announced related M&A, accounting for financial and organizational factors. We also explore additional strategic forces that might amplify or attenuate the negative effect of relatedness on deal completion. We test and find support for our hypotheses using longitudinal data from a sample of the largest M&A announcements in the world from 1991 to 2001.

Debt enforcement and relational contracting

We examine how third-party debt enforcement affects the emergence and performance ofrelational contracts in credit markets. We implement an experiment with finitely repeatedcredit relationships in which borrowers can default. In the weak enforcement treatmentdefaulting borrowers can keep their funds invested. In the strong enforcement treatmentdefaulting borrowers have to liquidate their investment. Under weak enforcement fewerrelationships emerge in which loans are extended and repaid. When such relationships doemerge they exhibit a lower credit volume than under strong enforcement. These findingssuggest that relational contracting in credit markets requires a minimum standard of thirdpartydebt enforcement.

Contagion or Interdependence in the recent Global Financial Crisis? An application to the stock markets using unconditional cross-market correlations

We consider stock market contagion as a significant increase in cross-market linkages after a shock to one country or group of countries. Under this definition we study if contagion occurred from the U.S. Financial Crisis to the rest of the major stock markets in the world by using the adjusted (unconditional) correlation coefficient approach (Forbes and Rigobon, 2002) which consists of testing if average crossmarket correlations increase significantly during the relevant period of turmoil. We would not reject the null hypothesis of interdependence in favour of contagion if the increase in correlation only suggests a continuation of high linkages in all state of the world. Moreover, if contagion occurs, this would justify the intervention of the IMF and the suddenly portfolio restructuring during the period under study.

Aggregate shocks or vertical tax interdependence? Evidende from gasoline and cigarettes

[cat] Besley i Rosen -1998- van ser els primers autors en estimar empíricament la rellevància de les externalitats impositives verticals. Aquests autors varen fer-ho per al cas dels impostos sobre la benzina i el tabac, en concret, per al cas dels EEUU. Ara bé, no varen tenir en compte les diferències en el nivell de vida entre Estats: àrees amb un nivell elevat paguen menys en termes reals que àrees amb un nivell de vida baix, doncs l'impost unitari sobre la benzina o sobre el tabac no difereix d'acord amb l'Estat on l'impost s'aplica. En conseqüència, proposem que la competència impositiva vertical sigui estimada deflactant totes les variables monetàries utilitzant l'anomenat "House Price Index (HPI)", el qual està disponible al nivell dels Estats. Això genera una variable impositiva federal expressada en termes reals i que presenta variació entre Estats. Aquesta estratègia empírica ens permet diferenciar entre la interdependència vertical entre els tipus impositius federals i els estatals de shocks agregats al llarg del temps, utilitzant dades per als EEUU durant el període 1975 a 2006 per a benzina i tabac. Trobem una nivell significatiu de competència impositiva horitzontal, la qual és més elevada en el cas del tabac, però en cap cas reacció impositiva vertical. Els resultats són robustos al període analitzat.

Aggregate shocks or vertical tax interdependence? Evidende from gasoline and cigarettes

[cat] Besley i Rosen -1998- van ser els primers autors en estimar empíricament la rellevància de les externalitats impositives verticals. Aquests autors varen fer-ho per al cas dels impostos sobre la benzina i el tabac, en concret, per al cas dels EEUU. Ara bé, no varen tenir en compte les diferències en el nivell de vida entre Estats: àrees amb un nivell elevat paguen menys en termes reals que àrees amb un nivell de vida baix, doncs l'impost unitari sobre la benzina o sobre el tabac no difereix d'acord amb l'Estat on l'impost s'aplica. En conseqüència, proposem que la competència impositiva vertical sigui estimada deflactant totes les variables monetàries utilitzant l'anomenat "House Price Index (HPI)", el qual està disponible al nivell dels Estats. Això genera una variable impositiva federal expressada en termes reals i que presenta variació entre Estats. Aquesta estratègia empírica ens permet diferenciar entre la interdependència vertical entre els tipus impositius federals i els estatals de shocks agregats al llarg del temps, utilitzant dades per als EEUU durant el període 1975 a 2006 per a benzina i tabac. Trobem una nivell significatiu de competència impositiva horitzontal, la qual és més elevada en el cas del tabac, però en cap cas reacció impositiva vertical. Els resultats són robustos al període analitzat.

Evaluación del estándar SQL:1999 respecto a las características orientadas al objeto que soporta y su implementación a los SGBD object-relational

Memoria de TFC en el que se analiza el estándar SQL:1999 y se compara con PostgreeSQL y Oracle.

Description of a robotics-oriented relational positioning methodology

This paper presents a relational positioning methodology for flexibly and intuitively specifying offline programmed robot tasks, as well as for assisting the execution of teleoperated tasks demanding precise movements.In relational positioning, the movements of an object can be restricted totally or partially by specifying its allowed positions in terms of a set of geometric constraints. These allowed positions are found by means of a 3D sequential geometric constraint solver called PMF – Positioning Mobile with respect to Fixed. PMF exploits the fact that in a set of geometric constraints, the rotational component can often be separated from the translational one and solved independently.

Hippocampal Theta-Phase Modulation of Replay Correlates with Configural-Relational Short-Term Memory Performance

Thereis now growing evidencethatthe hippocampus generatestheta rhythmsthat can phase biasfast neural oscillationsinthe neocortex, allowing coordination of widespread fast oscillatory populations outside limbic areas. A recent magnetoencephalographic study showed that maintenance of configural-relational scene information in a delayed match-to-sample (DMS) task was associated with replay of that information during the delay period. The periodicity of the replay was coordinated by the phase of the ongoing theta rhythm, and the degree of theta coordination during the delay period was positively correlated with DMS performance. Here, we reanalyzed these data to investigate which brain regions were involved in generating the theta oscillations that coordinated the periodic replay of configural- relational information. We used a beamformer algorithm to produce estimates of regional theta rhythms and constructed volumetric images of the phase-locking between the local theta cycle and the instances of replay (in the 13- 80 Hz band). We found that individual differences in DMS performancefor configural-relational associations were relatedtothe degree of phase coupling of instances of cortical reactivations to theta oscillations generated in the right posterior hippocampus and the right inferior frontal gyrus. This demonstrates that the timing of memory reactivations in humans is biased toward hippocampal theta phase

A relational approach to the geography of innovation: a typology of regions

The aim of this study was to devise a method for computing a composite indicator that measures the regional degree of exposure to external knowledge sources. On the basis of this indicator, we propose a typology of regions according to their potential capacity to access extra-local items of knowledge, which might help them to recombine complementary elements of such an asset to produce a higher number of new ideas. Building on various research streams that have been relatively independent to date, we summarize a non-exhaustive instrumental list of recent studies that motivates our approach and the construction of our complex indicator, which can be used to appraise the extent to which each region is in an optimal position to access external innovative resources.

Managing induced tourism image : relational patterns and the life cycle

The tourism image is an element that conditions the competitiveness of tourism destinations by making them stand out in the minds of tourists. In this context, marketers of tourism destinations endeavour to create an induced image based on their identity and distinctive characteristics.A number of authors have also recognized the complexity of tourism destinations and the need for coordination and cooperation among all tourism agents, in order to supply a satisfactory tourist product and be competitive in the tourism market. Therefore, tourism agents at the destination need to develop and integrate strategic marketing plans.The aim of this paper is to determine how cities of similar cultures use their resources with the purpose of developing a distinctive induced tourism image to attract tourists and the extent of coordination and cooperation among the various tourism agents of a destination in the process of induced image creation.In order to accomplish these aims, a comparative analysis of the induced image of two cultural cities is presented, Girona (Spain) and Perpignan (France). The induced image is assessed through the content analysis of promotional brochures and the extent of cooperation with in-depth interviews of the main tourism agents of these destinations.Despite the similarities of both cities in terms of tourism resources, results show the use of different attributes to configure the induced image of each destination, as well as a different configuration of the network of tourism agents that participate in the process of induced image creation

Firm Size and Short-Term Dynamics in Aggregate Entry and Exit

Much of the research on industry dynamics focuses on the interdependence between the sectorial rates of entry and exit. This paper argues that the size of firms and the reaction-adjustment period are important conditions missed in this literature. I illustrate the effects of this omission using data from the Spanish manufacturing industries between 1994 and 2001. Estimates from systems of equations models provide evidence of a conical revolving door phenomenon and of partial adjustments in the replacement-displacement of large firms. KEYWORDS: aggregation, industry dynamics, panel data, symmetry, simultaneity. JEL CLASSIFICATION: C33, C52, L60, L11

The missing link in key sectors analysis

In general terms key sectors analysis aims at identifying the role, or impact, that the existence of a productive sector has in the economy. Quite a few measures, indicators and methodologies of varied complexity have been proposed in the literature, from multiplier sums to extraction methods, but not without debate about their properties and their information content. All of them, to our knowledge, focus exclusively on the interdependence effects that result from the input-output structure of the economy. By so doing the simple input-output approach misses critical links beyond the interindustry ones. A productive sector’s role is that of producing but also that of generating and distributing income among primary factors as a result of production. Thus when measuring a sector’s role, the income generating process cannot and should not be omitted if we want to better elucidate the sector’ economic role. A simple way to make the missing income link explicit is to use the SAM (Soci