http://www.paper.edu.cn
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An Algorithmic Method to Extend Grey Relational Analysis
for Group Decision Making Problems under Fuzzy
Environment
Wei Guiwu
1,2
1. School of Economics and Management, Southwest Jiaotong University, Chengdu,
China (610031)
2. Department of Mathematics, North Sichuan Medical College, Nanchong, China (637007)
E-mail:weiguiwu@163.com
Abstract
The aim of this paper is to extend the grey relational analysis (GRA) to the fuzzy environment. Owing
to vague concepts frequently represented in decision data, the crisp value are inadequate to model real-
life situation. In this paper, the rating of each alternative and the weight of each criterion are described
by linguistic terms which can be expressed in triangular fuzzy numbers. Then a vertex method is used
to calculate the distance between two triangular fuzzy numbers. According to the concept of the GRA,
a fuzzy relative relational degree is defined to determine the ranking order of all alternatives by
calculating the degree of fuzzy grey relational coefficient to both the fuzzy positive-ideal solution
(FPIS) and fuzzy negative-ideal solution (FNIS) simultaneously. Finally, an example is given to show
the feasibility and effectiveness of the proposed method.
Keywords: Grey relational analysis (GRA); Linguistic variables; Triangular fuzzy numbers;
Multiple
criteria decision making (MCDM)
1. Introduction
There are a lot of multiple criteria decision making (MCDM) problems in our daily life. These
MCDM problems might include whether or not a person should buy a house or rent an apartment
either in urban or rural area because of the budget, quality of life, convenience, etc. The decision
maker (DM) should make a decision to determine which alternative is better if several criteria are
to be met. So, MCDM problems generally consist of finding the most desirable alternative(s) from
a given alternative set. Sometime, in the process of decision-making, the DM generally needs to
compare a set of decision alternatives with respect to a single criterion, and then to construct a
judgement matrix with a scale of 1 to 9
[1]
. However, many decision-making processes, in the real
world, take place in an environment in which the information is not precisely known. The DM
may have vague knowledge about degree of one alternative over another, and can’t estimate
his/her preference with an exact numerical value, but with an interval number or a triangular fuzzy
number. In 2002,Xu
[2]
study the fuzzy multiple criteria decision making (FMCDM), in which the
criteria weight information is incomplete, and the elements in decision-making matrix and
subjective preference values are triangular fuzzy numbers, and proposed a similarity degree
method. By using this method, a linear programming model is established firstly, and the criteria
weights are derived by solving this model, then, based on a possibility degree formula for
comparing two triangular fuzzy numbers and a formula for priorities of complementary judgement
matrix, a priority method for alternatives is presented. In 2004,Xu
[3]
study the FMCDM problems
again, proposed a new method based on expected values of the triangular fuzzy numbers is given.
Grey relational analysis (GRA) method was originally developed by Deng and has been
widely used to solve the uncertainty problems under the discrete data and information
incompleteness
[4-8]
.In addition, GRA method is one of the very popular methods to analyze various
relationships among the discrete data sets and make decisions in multiple criteria situations. The
major advantages of the GRA method are that the results are based on the original data, the
calculations are simple and straightforward, and, finally, it is one of the best methods to make