Give peace a chance: the effect of incomplete and imperfect information on mediation

In this paper we study mediation when two countries might fight a war over the ownership of a resource. Under complete information mediation is always successful, but a little bit of asymmetric information or some imperfect observability may render mediation impossible

Visualization and evolution of the scientific structure of fuzzy sets research in Spain

Introduction. Presents the first bibliometric study on the evolution of the fuzzy sets theory field. It is specially focused on the research carried out by the Spanish comunity. Method. The CoPalRed software, for network analysis, and the co-word analysis technique are used. Analysis. Bibliometric maps showing the main associations among the main concepts in the field are provided for the periods 1965-1993, 1994-1998, 1999-2003 and 2004-2008. Results. The bibliometric maps obtained provide insight into the structure of the fuzzy sets theory research in the Spanish community, visualize the research subfields, and show the existing relationships between those subfields. Furthermore, we compare the Spanish community with other countries (the USA and Canada; the UK and Germany; and Japan and Peoples Republic of China). Conclusions. As a result of the analysis, a complete study of the evolution of the Spanish fuzzy sets community and an analysis of its international importance are presented.Introducción. Presenta el primer estudio bibliométrico sobre la evolución del campo de la teoría de conjuntos difusos. Se centra especialmente en la investigación llevada a cabo por la comunidad española. Método. Se utiliza el software de CoPalRed, para el análisis de red, y la técnica de anñlisis de co-palabras. Aná;lisis. Se proporcionan mapas bibliométricos mostrando las principales asociaciones entre los principales conceptos en el campo para los períodos de 1965-1993, 1994-1998, 1999-2003 y 2004-2008. Resultados. Los mapas bibliométricos obtenidos proporcionan conocimientos sobre la estructura de la investigación sobre teoría de conjuntos difusos en la comunidad española, visualizan los subcampos de investigación y muestran las relaciones existentes entre los subcampos. Ademñs, se compara la comunidad española con otros países (Estados Unidos y Canada; Reino Unido y Alemania; y Japón y República Popular China). Conclusiones. Como resultado de los análisis, se presenta un estudio completo de la evolución de la comunidad española en conjuntos difusos y un anñlisis de su importancia internacional.This work has been supported by the Spanish project FUZZY-LING, Cod. TIN2007-61079, granted by the Spanish Agency for Education and Science (Ministerio de Educación y Ciencia)

A Variance-Based Consensus Degree in Group Decision Making Problems

The variance is a well-known statistical measure and is frequently used for the calculation of variability. This concept can be used to obtain the degree of agreement in groups that have to make decisions. In this study, we propose the use of a variance derivative as an alternative for the calculation of the degree of consensus for Group Decision Making problems with fuzzy preference relations. As revealed by a subsequent comparative study, the values obtained by this new method are comparable to the values obtained by means of frequently used methods that employ distance functions and aggregation operators, while it turns out to be a simpler application method

Linguistic Consensus Models Based on a Fuzzy Ontology

The main purpose of a Group Decision Making model is to reach a consensual solution as quickly as possible by decreasing the gap between the perceptions of different decision makers. The perception of the decision makers depends on the various relations between alternatives and attributes. As a real life example, one can mention the present problem of the euro crisis: before finding a solution for the situation, the different perceptions of each country have to be attuned to have a common ground for negotiations. We have to cope with two different issues when modeling a Group Decision Making problem: (1) the relations describing alternatives and attributes are known only partially in most of the cases and (2) these relations change dynamically. Fuzzy ontologies can provide a solution to handle both issues in an efficient way: we can model incomplete and uncertain information using the well-established theory of fuzzy logic and we can dynamically model the changes in the structure by employing ontologies. Therefore, we propose a new linguistic extension of a consensus model to deal with the psychology of negotiation by using the power of a fuzzy ontology as weapon of influence in order to improve group decision scenarios making them more precise and realistic.European Union (EU)FUZZYLING-II TIN2010-17876Andalusian Excellence Projects TIC-05299 TIC-5991Finnish Funding Agency for Technology & Innovation (TEKES) 40039/1

The dynamics of consensus in group decision making: investigating the pairwise interactions between fuzzy preferences.

In this paper we present an overview of the soft consensus model in group decision making and we investigate the dynamical patterns generated by the fundamental pairwise preference interactions on which the model is based. The dynamical mechanism of the soft consensus model is driven by the minimization of a cost function combining a collective measure of dissensus with an individual mechanism of opinion changing aversion. The dissensus measure plays a key role in the model and induces a network of pairwise interactions between the individual preferences. The structure of fuzzy relations is present at both the individual and the collective levels of description of the soft consensus model: pairwise preference intensities between alternatives at the individual level, and pairwise interaction coefficients between decision makers at the collective level. The collective measure of dissensus is based on non linear scaling functions of the linguistic quantifier type and expresses the degree to which most of the decision makers disagree with respect to their preferences regarding the most relevant alternatives. The graded notion of consensus underlying the dissensus measure is central to the dynamical unfolding of the model. The original formulation of the soft consensus model in terms of standard numerical preferences has been recently extended in order to allow decision makers to express their preferences by means of triangular fuzzy numbers. An appropriate notion of distance between triangular fuzzy numbers has been chosen for the construction of the collective dissensus measure. In the extended formulation of the soft consensus model the extra degrees of freedom associated with the triangular fuzzy preferences, combined with non linear nature of the pairwise preference interactions, generate various interesting and suggestive dynamical patterns. In the present paper we investigate these dynamical patterns which are illustrated by means of a number of computer simulations.

Résolution des problèmes de décision de groupe par analyse bipolaire

On entend par décision de groupe ici, la sélection par plusieurs décideurs, d’une ou plusieurs alternatives dans un ensemble vaste d’alternatives. Du fait de l’existence de plusieurs acteurs, le processus de décision doit tenir compte des relations d’influence (positive ou négative) qui peuvent exister entre les acteurs de la décision. De même, l’évaluation des alternatives par rapport aux objectifs des décideurs doit se faire en considérant plusieurs critères ou attributs caractérisant ces alternatives positivement ou négativement. Cette dualité, que ce soit au niveau des relations entre décideurs ou au niveau des relations entre attributs caractérisant les alternatives et les objectifs, est prise en compte dans ce papier à travers la notion de bipolarité. Ainsi, les relations entre décideurs seront évaluées à travers des mesures de concordance et de discordance et les relations entre attributs et objectifs à travers les notions de supportabilité et de rejetabilité. Au final, pour chaque décideur une alternative sera évaluée, par deux mesures ; une mesure de sélectabilité qui agrège les aspects positifs de l’alternative et une mesure de rejetabilité qui agrège les aspects négatifs dans le formalisme des jeux satisfaisants. Un processus de recherche de consensus entre décideurs est proposé pour aboutir à une solution finale dans le cas où aucune alternative ne satisfait simultanément tous les décideurs

Supplier selection in risk consideration: a fuzzy based topsis approach

Supplier selection, the process of finding the right suppliers who are able to provide the buyer with the right quality products and/or services at the right price, at the right time and in the right quantities, is one of the most critical activities for establishing an effective supply chain. In classical Multi-Criteria Decision Making (MCDM) methods, the ratings and the weights of the criteria are known precisely. Owning to vagueness of the decision data, the crisp data are inadequate for real-life situations. Since human judgments including preferences are often vague and cannot be expressed by exact numerical values, the application of fuzzy concepts in decision making is deemed to be relevant. On the other hand, it is a hard problem since supplier selection is typically a MCDM problem involving several conflicting criteria on which decision maker’s knowledge is usually vague and imprecise. In the present work, a risk-based suppliers’ evaluation module is proposed. Linguistic values are used to assess the ratings and weights for the risk based supplier selection factors. These linguistic ratings can be expressed in triangular fuzzy numbers. Then, a hierarchy MCDM model based on fuzzy-sets theory is proposed to deal with the supplier selection problems in the supply chain system. According to the concept of the fuzzy TOPSIS (Technique for Order Preference by Similarity to Ideal Solution), a closeness coefficient is defined to determine the ranking order of all suppliers by calculating the both fuzzy positive-ideal solution and fuzzy negative-ideal solution, simultaneously. Empirical data have been analysed and results obtained thereof, have been reported to exhibit application potential of the decision-support systems in appropriate situation

Employing zSlices based general type-2 fuzzy sets to model multi level agreement

In this paper, we introduce the concept of Multi Level Agreement (MLA) based on (zSlices based) general type-2 fuzzy sets. We define the notion of MLA and describe how it can be computed based on a series of interval type-2 fuzzy sets. We provide examples, visualizing the nature of MLA sets and discuss their properties and interpretation. Moreover, we specifically address the reason for introducing MLA in order to allow the modeling of agreement in real world applications using fuzzy sets while still maintaining an uncertainty model and show that the use of general type-2 fuzzy sets is essential for MLA as classical sets, type-1 and interval type-2 fuzzy sets do not provide a degree of freedom which could be employed to model agreement. © 2011 IEEE

Reaching Consensus in Digital Libraries: A Linguistic Approach

This work has been developed with the financing of FEDER funds in FUZZYLING-II Project TIN2010-17876, the Andalusian Excellence Projects TIC-05299 and TIC-5991, and Proyecto de Investigación del Plan de Promoción de la Investigación UNED 2011 (2011/PUNED/0003)2nd International Conference on Information Technology and Quantitative Management, ITQM 2014Libraries are recently changing their classical role of providing stored information into new virtual communities, which involve large number of users sharing real time information. Despite of those good features, there is still a necessity of developing tools to help users to reach decisions with a high level of consensus in those new virtual environments. In this contribution we present a new consensus reaching tool with linguistic preferences designed to minimize the main problems that this kind of organization presents (low and intermittent participation rates, difficulty of establishing trust relations and so on) while incorporating the benefits that a new digital library offers (rich and diverse knowledge due to a large number of users, real-time communication and so on). The tool incorporates some delegation and feedback mechanisms to improve the speed of the process and its convergence towards a consensual solution.FEDER funds in FUZZYLING-II Project TIN2010-17876Andalusian Excellence Projects TIC-05299 and TIC-5991Proyecto de Investigación del Plan de Promoción de la Investigación UNED 2011 (2011/PUNED/0003