Eliciting comparative linguistic expressions in group decision making

The complexity and relevance of the real world decision making problems have made necessary to use multiple points of view to achieve a common solution by using the knowledge provided for a group of experts. Usually, this knowledge is vague and imprecise. In such cases, the use of linguistic information has provided successful results, although sometimes they are limited because of the linguistic models restrict the elicitation of the linguistic information to single linguistic terms. In qualitative settings there is a high degree of uncertainty, in which experts can hesitate among several linguistic terms to provide their preferences. Therefore, richer expressions than single linguistic terms might support experts in such hesitant situations and improve the preferences elicitation and decision results. In this contribution, it is proposed a new group decision making model able to manage complex linguistic expressions based on hesitant fuzzy linguistic term sets and context-free grammars. The proposed model defines the necessary operations and tools to deal with such linguistic expressions.