A Hesitant Fermatean Fuzzy CoCoSo Method for Group Decision-Making and an Application to Blockchain Platform Evaluation

The existing score functions of Fermatean fuzzy number (FFN) show some defects. In addition, the evaluation information given by decision-makers in real decision-making processes may be several discrete values rather than single value, which cannot be represented by the classical Fermatean fuzzy set (FFS). The combined compromise solution (CoCoSo) method can get a compromise solution by incorporating multi-aggregation strategy; however, the final aggregation operator adopted in the CoCoSo method may cause irrational results. To bridge the above gaps, in this study, we first determine a new score function of FFNs. Then, we define the hesitant Fermatean fuzzy sets based on hesitant fuzzy sets and FFSs to process uncertain information flexibly. Next, we develop an ensemble ranking approach to overcome the limitation of the original CoCoSo method regarding aggregation bias. Afterwards, we propose a hesitant Fermatean fuzzy CoCoSo method for multiple criteria group decision-making. Last, we verify its effectiveness and practicability through a case study on the selection of blockchain platform. At the same time, we perform sensitivity analysis to check the robustness of the method, and emphasize its advantages through comparative analysis.