Abstract
The novel concept of the complex interval-valued T-spherical fuzzy set (CIVTSFS) is presented to handle the vagueness in the data. The proposed set takes the advantages of interval-valued spherical fuzzy sets and complex numbers to represent the information in terms of the interval-valued number of the truth, abstinence and falsity degrees. Various operation laws are stated to enrich the features of CIVTSFS. By utilising the proposed laws, several weighted operators are stated to aggregate the different preference of the experts towards the evaluation of the alternatives. Furthermore, a group decision-making algorithm is stated to solve the decision-making problems by utilising the uncertain data under CIVTSFS information. The presented algorithm is demonstrated through a numerical example and their advantages are indicated.