Similarity and entropy measures for circular intuitionistic fuzzy sets

A recent extension of intuitionistic fuzzy sets (IFSs) is the circular intuitionistic fuzzy set (C-IFS), where the performance of each alternative is described by a circle with a fixed radius rather than a specific orthopair. This article presents the similarity and dissimilarity measures for C-IFSs. Their basic axioms are proven, and some of their characteristics are brought to light. The axiomatic definition of entropy measures for C-IFSs is given. Several mathematical expressions are provided to measure the entropy of C-IFSs. The conversions of entropy into similarity measures and from similarity into entropy are given. The inferior ratio method, which relies on similarity measures, is extended for the C-IFS framework. The method is illustrated through a case study of site selection for an epidemic hospital. The solutions of the given approach are compared with the existing decision-making techniques.