A consensus reaching process dealing with comparative linguistic expressions for group decision making: A fuzzy approach

Group Decision Making (GDM) deals with decision problems in which multiple experts, with their own attitudes and knowledge, evaluate different alternatives or solutions with the aim of achieving a common solution. In such cases disagreements can appear, which might led to failed solutions. To manage such conflicts, Consensus Reaching Processes (CRPs) have been added to the GDM solving process. GDM problems under uncertainty often model uncertainty by linguistic descriptors, being most of linguistic based CRPs based on the use of single linguistic terms for modelling experts' opinions, which cannot be expressive enough in some situations because of either the uncertainty involved or the experts' hesitancy. Therefore, this paper aims to fill this gap by proposing a novel consensus model dealing with GDM problems in which experts' preferences are elicited by means of Comparative Linguistic Expressions (CLEs) based on Hesitant Fuzzy Linguistic Term Sets, which allow to model the experts' hesitancy in a flexible way. Furthermore, CLEs are modelled by fuzzy membership functions in order to keep the fuzzy representation in the whole CRP and preserve as much information as possible. Additionally, the proposed model is implemented and integrated in an intelligent CRP support system, so-called AFRYCA 3.0 to carry out a case study about this new CRP and compare it with previous models.