Group Decision Making Research Under Interval-valued Hesitant Fuzzy Environment

In the process of group decision making,because of the complexity and uncertainty of objective decision making problems,and the limitations of human's knowledge reserve and cognitive ability,some preference information is difficult to use exact value to describe.Some properties of interval numbers and hesitant fuzzy sets are included in the interval valued hesitant fuzzy sets,the real preference of decision makers can be expressed by interval valued hesitant fuzzy sets.The conclusion which obtained by interval valued hesitant fuzzy decision making are more proximate to the practical situation.Therefore,the research on hesitant fuzzy group decision making theory and application seems to be realistic and important.There exist some drawbacks in the existing decision making methods.In this thesis,the order relation and group decision making problems under the interval valued hesitant fuzzy environment are analyzed and studied,the details as follows:(1)Order relation plays important rules in decision making procedure.In the existing decision making methods,there exist some drawbacks,such as lacks flexibility and significant information may be distorted and lost.To overcome certain drawbacks of the existing ordering relation between two interval-valued hesitant fuzzy sets,priority degree formula and geometric mean priority degree formula for two interval-valued hesitant fuzzy sets are proposed,and the desirable properties are studied.(2)The interval-valued hesitant fuzzy possibility degree is defined based on the extension of interval number possibility degree,and its properties are studied.(3)The priority degree and geometric mean priority degree are applied to the group decision problems,and new interval-valued hesitant fuzzy group decision methods are constructed accordingly.To further extend the priority degree,based on the TOPSIS and PROMETHEE thoughts,the thesis puts forward two kinds of approach:A TOPSIS group decision making approach based on the priority degree,a PROMETHEE group decision making approach based on the priority degree.Numerical examples are given,which illustrated the rationality and validity of the new approach.