Group decision making systems using group recommendations based on interval fuzzy preference relations and consistency matrices

In this paper, we present a new method for group decision making using group recommendations based on interval fuzzy preference relations and consistency matrices. First, the proposed method constructs the collective consistency matrix, the weighted collective preference relation, and the group collective preference relation. Then, it constructs a consensus relation for each expert and calculates the group consensus degree of all experts. If the group consensus degree is smaller than a predefined threshold value, then it marks the consensus values in each consensus relation which are smaller than the group consensus degree and modifies the interval fuzzy preference values corresponding to the marked consensus values. The above process is performed repeatedly, until the group consensus degree is larger than or equal to the predefined threshold value. Finally, based on the group collective preference relation, it calculates the score of each alternative for ranking the preference order of the alternatives. The proposed method can overcome the drawbacks of the existing methods for group decision making. It provides us with a useful way for group decision making using group recommendations based on interval fuzzy preference relations and consistency matrices.