Improved Hesitant Intuitionistic Fuzzy Linguistic Term Sets and Their Application in Group Decision-Making

Linguistic terms have proven to be more effective for DMs when defining complex and imprecise cognition. Consequently, a variety of novel linguistic models such as fuzzy linguistic approach, hesitant fuzzy linguistic term sets (HFLTSs), and hesitant intuitionistic fuzzy linguistic term sets (HIFLTSs) have been successively proposed. As HIFLTSs provide an effective and symmetrical technique for expressing qualitative decisions by decision-makers, they have attracted substantial scholarly interest. This paper proposes a series of new operational laws to address the current limitations and enhance the applicability and methodology of HIFLTSs. Additionally, we introduce a new score function and an accuracy function that both consider the degree of hesitancy, thus addressing the current shortcomings. Furthermore, the correlation measures and correlation coefficients are established to enrich the framework of the HIFLTSs theory. Finally, a MULTIMOORA approach in the HIFLTS environment is presented, which results in more robustness, simplicity, and effectiveness. A practical example is employed to demonstrate the effectiveness of the proposed approach, and a comparison with related works highlights the advantages and novelty of the proposed model.