Mathematical Problems in Engineering

Volume 2016, Article ID 4274690, 16 pages

http://dx.doi.org/10.1155/2016/4274690

## An Extended VIKOR Method for Multiple Attribute Decision Analysis with Bidimensional Dual Hesitant Fuzzy Information

^{1}School of Management, Hefei University of Technology, P.O. Box 270, Hefei, Anhui 230009, China^{2}Key Laboratory of Process Optimization and Intelligent Decision-Making, Ministry of Education, P.O. Box 270, Hefei, Anhui 230009, China

Received 26 May 2016; Accepted 1 August 2016

Academic Editor: Yong Deng

Copyright © 2016 Min Xue et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### Abstract

Bidimensional dual hesitant fuzzy (BDHF) set is developed to present preferences of a decision maker or an expert, which is more objective than existing fuzzy sets such as Atanassov’s intuitionistic fuzzy set, hesitant fuzzy set, and dual hesitant fuzzy set. Then, after investigating some distance measures, we define a new generalized distance measure between two BDHF elements with parameter for the sake of overcoming some drawbacks in existing distance measures. Covering all possible values of parameter , a new approach is designed to calculate the generalized distance measure between two BDHF elements. In order to address complex multiple attribute decision analysis (MADA) problems, an extension of fuzzy VIKOR method in BDHF context is proposed in this paper. In VIKOR method for MADA problems, weight of each attribute indicates its relative importance. To obtain weights of attributes objectively, a new entropy measure with BDHF information is developed to create weight of each attribute. Finally, an evaluation problem of performance of people’s livelihood project in several regions is analyzed by the proposed VIKOR method to demonstrate its applicability and validity.

#### 1. Introduction

Multiple attribute decision analysis (MADA) is used to deal with the problems of making an optimal choice from alternatives or generating a ranking order of alternatives in terms of attributes [1, 2]. In order to deal with MADA problems, many decision analysis methods have been proposed, such as outranking method [3, 4], TOPSIS (technique for order preference by similarity to ideal solution) [5–7] method, aggregation operator-based methods [8, 9], and VIKOR (VIšeKriterijumska Optimizacija I Kompromisno Rešenje) [10, 11]. Hereinto, due to the characteristics and capabilities of VIKOR method, it has received much attention from academic and practical fields [12, 13]. VIKOR method mainly focuses on ranking and selecting from a set of alternatives and determines compromise solutions for a MADA problem with conflicting attributes [14, 15]. It represents “closeness to the ideal” in the process of addressing MADA problems. In general, VIKOR method with respect to MADA includes three major steps: the collection of a decision maker’s preferences; the calculation of closeness to the ideal; and the determination of attribute weights.

In practical MADA problems, the decision maker may feel difficulty in expressing his/her preferences exactly for the reasons of environmental uncertainty, the limitation of his/her knowledge and experience, and the urgency of time. To address such situations, many expression forms are developed to express information of a decision maker, such as interval-valued number [16], linguistic term set [17], fuzzy set [18, 19], hesitant fuzzy (HF) set [20], Atanassov’s intuitionistic fuzzy (AIF) set [3, 21], and dual hesitant fuzzy (DHF) set [22]. In some situations, they are not available. Taking a supplier selection problem as an example, there are a supplier denoted by and three experts denoted by , , and . Suppose that two experts (e.g., and ) consider the preference intensity that supplier should be selected and deselected to be 0.7 and 0.1, respectively. Meanwhile, an expert (e.g., ) considers the preference intensity that supplier should be selected and deselected is 0.5 and 0.3, respectively. Therefore, the overall preference of the three experts can be denoted by which is a DHF assessment. Here, the preference intensity that supplier should be selected or deselected means the membership degree or nonmembership degree of experts’ preference, respectively. The DHF assessment seems to express the whole preference of the three experts in this supplier selection problem, but it cannot reflect the support intensity of specific membership degrees or that of nonmembership degrees. Here, support intensity means proportion of experts supporting the preference intensity. In the example mentioned above, the support intensity of membership degree 0.7 is different from that of membership degree 0.5. Such a difference has not been reflected in the DHF assessment. In fact, the support intensity of membership degree 0.7 is 2/3 0.67, while the support intensity of membership degree 0.5 is 1/3 0.33, without considering the fact that the differences in support intensity of various assessments could result in different final decisions. Similarly, the support intensity of the other possible nonmembership degrees can be obtained. Thus, it should be noted from the analysis of this example that membership or nonmembership degrees and their support intensity are two aspects of an assessment and should not be neglected in the process of decision making. However, there have been few studies concerning the support intensity of possible membership degrees or that of nonmembership degrees so far. For this reason, in this paper, based on the support intensity and motivated by the idea of DHF set, a new expression form, that is, bidimensional dual hesitant fuzzy (BDHF) set, is developed to present preference information of a decision maker.

In order to address MADA problems with BDHF information, this paper proposes an extended VIKOR method. Firstly, a new generalized distance measure between BDHF sets is proposed to compare alternatives in MADA. This distance measure, as the generalization of existing distance measures, such as AIF distance measure [23, 24] and HF distance measure [25, 26], can relax the following two potential conditions of existing HF distance measures: the possible membership degrees in HF element should be arranged in an increasing or decreasing order; and the shorter one in two HF elements can be extended by adding the same value several times until they have the same length. Obviously, it can avoid missing or changing original information provided by the decision maker and may further avoid influence of the two conditions on the final decision result. The details of the distance measure will be demonstrated in Section 3. Moreover, there is parameter in distance measure impacting the value of distance measure. However, in existing literatures, few studies state how to obtain the value of parameter scientifically. Thus, to avoid the negative influence of arbitrary or subjective values of parameter on the value of distance measure between BDHF assessments, an average distance measure covering all the possible types of the generalized distance measures instead of determining an exact value of parameter is proposed to calculate the distance measure between two BDHF assessments in VIKOR method. Secondly, an objective method of acquiring weight vector (e.g., entropy measure) is extended in BDHF context to objectively determine weight vector of each attribute. Here, corresponding properties of entropy measure are also investigated. Besides, based on the proposed VIKOR method with BDHF information in this paper, an assessment problem of people’s livelihood of different regions is demonstrated to verify applicability and validity of the proposed method. Finally, using the information related to the assessment problem, we compare TOPSIS with VIKOR to reflect the advantages of VIKOR method.

The main contributions of this paper include the following: the introduction of bidimensional dual hesitant fuzzy (BDHF) set; the definition of the generalized distance measure between BDHF assessments; the acquisition of attribute weights based on entropy measure with BDHF information; the comparison between VIKOR and TOPSIS method; and the development of a new VIKOR method with BDHF assessments.

The rest of this paper is organized as follows. Section 2 reviews some basic concepts. Section 3 proposes the concept of BDHF element and new generalized distance measure. Section 4 develops VIKOR method for MADA problems. Section 5 conducts an assessment problem of people’s livelihood project to demonstrate the validity and applicability of the proposed method and compares it with TOPSIS method. Finally, Section 6 concludes this paper.

#### 2. Review of Relevant Concepts

In this section, we review some concepts related to the proposed MADA method with BDHF information.

##### 2.1. Related Concepts of DHF Set

BDHF set can be regarded as a generalization of DHF set, as mentioned in Introduction. To make the concept of BDHF set clear, the concept of DHF set is introduced below. Here, DHF set can be considered a combination of AIF set and HF set.

*Definition 1 (see [22]). *Given a universe of discourse , a DHF set on is defined aswhere and symbolize the set of possible membership degrees and the set of nonmembership degrees of to , respectively, such that , , and for all .

Given and , is defined to symbolize possible indeterminacy (uncertain) set of to , where and represent possible membership and nonmembership degrees of to . When is given, is named as a DHF element, where denotes possible indeterminacy (uncertain) set of to .

It is noted that the lengths of different HF sets may be different and thus different DHF sets may also have various lengths.

##### 2.2. Distance Measure between AIF Information and That between HF Information

When VIKOR method is applied to analyze MADA problems, distances between decision information and ideal solutions are used to compare alternatives. As such, distance measure between BDHF information is needed for the developed method. Meanwhile, as a generalization of DHF set, BDHF set is closely related to AIF set and HF set. In order to effectively measure the distance among BDHF information, the existing generalized distance measure among AIF information and that among HF information are defined below.

*Definition 2 (see [24]). *Let and be two AIF numbers. Then, a generalized distance measure between and is defined aswhere represents a parameter to indicate different specific distance measures.

*Definition 3 (see [26]). *Let and be two HF elements where symbolizes the length of (). Then, a generalized distance measure between and is defined aswhere is a parameter to signify different specific distance measures and and denote the th largest membership degree in and , respectively. Specifically, is a permutation of such that and for all .

As mentioned in Section 2.1, it may be the case that the lengths of and are different in most practices. In order to make the distance measure applicable in such case, Xu and Xia [26] and Xu and Zhang [27] proposed some strategies to equalize the lengths of and . The prerequisite of these ways is to arrange the membership degrees in and in increasing or decreasing order. Then, the same value will be repeatedly added to the shorter HF element ( or ) until its length is the same as the length of the longer one. There are usually three strategies of adding values:(1)Optimists expect desirable outcomes and add the maximum value [26].(2)Pessimists anticipate unfavorable outcomes and may add the minimum value [26].(3)Neutrals look forward to unbiased outcomes and may add the average value [27].

In real life, even if the risk attitude of a decision maker is clear, the degree to which the decision maker prefers risk-seeking or risk-aversion may be also unknown. In other words, a decision maker with risk-seeking to some extent is not certainly sure that the maximum value should be added to the shorter HF element. It is the similar case for pessimists. More importantly, any strategy has no ability to perfectly reflect the original preference of a decision maker, especially when one or more values in HF element appear several times originally.

##### 2.3. Entropy Measure with AIF Information

In MADA, the entropy of decision information is usually employed to determine attribute weights. This idea is also adopted in the developed method. That is, the entropy of BDHF information is measured to create attribute weights. To do this, the entropy of AIF information is presented as necessary foundation.

*Definition 4 (see [28]). *A real function is called Atanassov’s intuitionisitc fuzzy entropy if satisfies the following axiomatic requirements for all sets (*X*):(1) if ( being nonfuzzy).(2) if for all .(3) if is less fuzzy than , that is, and for or and for .(4).

*Definition 5 (see [29]). *Let be an AIF set on the universe of discourse . Then, entropy measure with the AIF set is defined aswhere is the cardinality of the finite universe . This AIF entropy satisfies axiomatic conditions in Definition 4.

#### 3. BDHF Set and Distance Measure among BDHF Information

In this section, BDHF element is defined based on the concept of DHF element and the distance between BDHF elements is measured in order to develop the VIKOR method with BDHF information.

##### 3.1. Concept of BDHF Set

Reconsidering the supplier selection problem in Introduction, which is a MADA problem, we can find that when three experts give different preferences about selecting and deselecting one supplier, the union of the preferences can naturally form the DHF preference of a decision maker on the assumption that each expert is equivalently important for the decision maker. However, when two or three experts provide the same preference, the resulting DHF preference can be regarded as a transformation from dual intuitionistic fuzzy multiset to DHF set in the abstract [30]. Simply getting the union of the same preference in such transformation will inevitably result in the loss of original information. Any strategy in Section 2.2 cannot recover all original information and avoid information loss. To address this issue, we firstly introduce the concept of support intensity given that experts or others used to help a decision maker generate DHF preferences are considered information sources and then define BDHF set based on support intensity.

*Definition 6. *Suppose a decision maker provides a DHF element depending on information resources. Let the number of information sources supporting membership degree and that supporting nonmembership degree be, respectively, denoted by and satisfying and ; then the support intensity of membership degree and that of nonmembership degree are measured by and , respectively.

When introducing the concept of support intensity of membership and nonmembership degrees, information implied by dual intuitionistic fuzzy multiset can be effectively covered. That is, when dual intuitionistic fuzzy multiset is transformed into DHF set with support intensity of membership and nonmembership degrees, it can be recovered without information loss. Activated by this idea, DHF set is extended to be BDHF set, as defined below.

*Definition 7. *Let be a universe of discourse. A BDHF set on is defined aswhere and denote possible membership degree of to and its support intensity and possible nonmembership degree of to and its support intensity, in which , , , , and .

For simplicity, a BDHF element is still denoted by . Here, all original information including membership degree, nonmembership degree, and support intensity with the help of the information resources is effectively characterized in a BDHF element, which cannot be explicitly portrayed in a DHF element.

From Definition 1, it can be inferred that each membership degree in a DHF element can be combined with any nonmembership degree to form Atanassov’s intuitionistic fuzzy (AIF) number [22]. Similarly, a BDHF number as the extension of a DHF element can be transformed into several AIF numbers in decision making process such as the computation of distance measure. In this process, besides membership and nonmembership degrees, their support intensity as another important aspect of a BDHF element should be considered so as to complete this decision process. Thus, each AIF number involved in a BDHF element should also have specific support intensity which is a combination of support intensity of each of the membership and nonmembership degrees related to this AIF number. Here, how to obtain the support intensity of an AIF number involved in a BDHF element is a key problem. In order to tackle this issue, the following assumption is proposed.

*Assumption 8. *Based on the original information provided by all information resources, a decision maker can provide BDHF assessments related to some alternatives on several attributes. In this process, it is required for a decision maker that (1)a BDHF assessment once provided by the decision maker will not be changed no matter whether other BDHF assessments are known or not;(2)the decision maker specifies membership degrees in a BDHF assessment without considering nonmembership degrees;(3)the decision maker specifies nonmembership degrees in a BDHF assessment without considering membership degrees.

Assumption 8 means that any two BDHF assessments are mutually independent and any membership degree and nonmembership degree in a BDHF element are also mutually independent in a decision making process.

Then, under Assumption 8, support intensity of each AIF number involved in a BDHF element can be determined in order to complete all operations in a decision making process including the computation of distance measure as follows.

*Definition 9. *Let be a BDHF element where and symbolize the numbers of possible membership and nonmembership degrees, respectively. The combination of each AIF number and support intensity involved in a BDHF element can be defined as

Here, under Assumption 8, because of the independence between membership degree and nonmembership degree in any AIF number, it can be inferred that support intensity of an AIF number involved in a BDHF element is the product of that of corresponding membership and nonmembership degrees. Thus, the number of the AIF numbers involved in a BDHF element is . For example, given a BDHF element denoted by , then the combination of each AIF number involved in the BDHF element can be obtained as .

In addition, it can be obtained from Definition 1 that possible indeterminacy (uncertain) set of to DHF set is equal to which means the union where one subtracts the sum of any possible membership and nonmembership degrees. However, in a BDHF element, not only membership and nonmembership degrees but also their corresponding support intensity should be considered. Thus, based on Assumption 8 and Definition 9, we can infer that support intensity of possible indeterminacy (uncertain) degree of to BDHF set equals the product of support intensity of corresponding membership and nonmembership degrees, which is demonstrated in the following:where symbolizes possible indeterminacy (uncertain) set of to and and represent possible membership and nonmembership degrees and their corresponding support intensity of to .

Then, the basic operations of BDHF elements can be defined in the following.

*Definition 10. *Let* X* be a fixed set and and be two BDHF elements; the following operations are valid:(1)).(2).(3).(4).(5).Here, represents the complement of the BDHF element .

##### 3.2. Distance Measure between BDHF Elements

As mentioned in Introduction, the computation of distance measure between BDHF elements is a key step in the proposed VIKOR method. From Definition 11, it can be obtained that, in the process of measuring distance between two BDHF elements, any AIF number involved in one BDHF element and that in another BDHF element should be covered. That is, distance measure between two AIF numbers contributes to that between two BDHF elements. Thus, in order to define the distance measure between two BDHF elements, we should first design distance measure between two AIF numbers involved in two BDHF elements below.

*Definition 11. *Let and be any two AIF numbers from two BDHF elements, respectively. Then, the distance measure between and can be defined as follows: where is a parameter to signify different distance measures.

From Definition 9, besides distance measure between AIF numbers, the support intensity of each AIF number should be considered to calculate distance measure between BDHF elements. Then, under Assumption 8, because of the independence among any two BDHF elements, it can be obtained from Definition 9 that the support intensity of distance measure between two AIF numbers involved in two BDHF elements equals the product of the support intensity of these two AIF numbers, which is defined in the following.

*Definition 12. *Let and be two combinations of two AIF numbers and their support intensity involved in two BDHF elements, respectively. Then, the support intensity of distance measure between and can be defined as follows: where and denote support intensity of the 1st possible membership degree and the 1st possible nonmembership degree in , respectively.

Because the distance measure between BDHF elements consists of all combinations of AIF numbers with their support intensity, then, combining Definition 11 with Definition 12, the distance measure between two BDHF elements can be defined below.

*Definition 13. *Let and be two BDHF elements, where and symbolize the numbers of possible membership and nonmembership degrees, respectively. Then, the generalized distance measure between and can be defined as follows:where and denote support intensity of the th possible membership degree and the th possible nonmembership degree in , respectively. Similarly, and denote support intensity of the th possible membership degree and the th possible nonmembership degree in , respectively. In addition, can be obtained from Definition 11.

As analyzed in Section 2.2, the distance measure between HF elements in Definition 3 is based on several conditions which will constrain the application of this distance measure. From Definition 13, it is obvious that these conditions are relaxed.

Then, in order to demonstrate the process of calculating the distance measure in Definition 13 clearly, Example 14 is showed in the following.

*Example 14. *Let , and be two BDHF elements. Then, the generalized distance measure between and is calculated by Definition 13 as follows:

Obviously, it can be seen from Example 14 that the value of distance measure between and depends on the value of parameter . The final result will be demonstrated in Example 24.

Three special cases of the generalized distance measure in Definition 13 are presented in the following definitions.

*Definition 15. *When , the generalized distance measure in Definition 13 reduces to the Hamming distance measure:

*Definition 16. *When , the generalized distance measure in Definition 13 reduces to the Euclidean distance measure:

*Definition 17. *When , the generalized distance measure in Definition 13 reduces to the Chebyshev distance measure:

The generalized distance measure in Definition 13 has some properties including boundedness, commutativity, and conditional reflexivity, which are concluded in the following theorem.

Theorem 18. *Given two BDHF elements, and , the generalized distance measure in Definition 13 satisfies the following properties:*(1)*Boundedness is .*(2)*Commutativity is .*(3)*Conditional reflexivity is if , , , and .*

*Theorem 18 is proven in Section A.1 of Appendix A.*

*As mentioned in Definition 13, parameter is limited to . Determining the precise value of from the interval may be difficult, especially when various kinds of information are involved in the determination process. However, most existing studies arbitrarily or subjectively assign several special values to parameter without reasonable explanation, which may not always accord with practical situations. More importantly, it may lead to an unrealistic distance between two elements without appropriate parameter . To avoid the negative influence of arbitrary or subjective on distance between two elements, we use average value of the generalized distance measure between two BDHF elements to calculate the final distance measure with full coverage of the values of possible . Hereinto, the average value of the generalized distance measure could be considered a most likely result covering all possible types of distance measures.*

*Definition 19 (see [31]). *If a function is integrable on interval , then the average value of denoted by on can be defined as follows:

*Based on Definitions 13 and 19, the average value of the generalized distance measure is designed to calculate the final distance measure, which is presented as follows.*

*Definition 20. *Let be a generalized distance measure between two BDHF elements. Then the average value of the generalized distance measure is defined as In this equation, it is obvious that is divergent. Thus,* L’Hopital’s Rule* could be applied to calculate the value of as long as the following two conditions are satisfied: (1)The numerator of diverges.(2) exists.

*To achieve the mentioned work simply, we firstly design a new function denoted by representing a major part of . That is, if the average value of denoted by can be acquired, then the value of can be also calculated. Then, we investigate whether diverges and exists or not. Firstly, monotonicity of function with respect to is demonstrated in the following.*

*Lemma 21. Suppose that is a function with parameter where and . Then, is monotonous increasing with respect to and its upper bound is , that is,*

*Lemma 21 is proven in Section A.2 of Appendix A. It can be inferred from Lemma 21 that when approaches + ∝, will approximate to . It means that is divergent. In addition, it can be inferred from Lemma 21 that . Thus, L’Hopital’s Rule for forms of type in Lemma 22 could be applied to calculate the value of in Theorem 23.*

*Lemma 22 (see [31]). Suppose that . If exists in either the finite or infinite sense, thenHere, u may stand for any of the symbols , , , , or .*

*Theorem 23. Suppose that , where and . Then, the average value of denoted by equals .*

*Theorem 23 is proven in Section A.3 of Appendix A with the help of Lemma 21. It indicates from Theorem 23 that will represent the value of in the process of calculating a distance measure between two elements. Then, it can be obtained that the value of equals . Clearly, Theorem 23 can simplify computing process of distance measures and avoid the difficulty of determining appropriate parameter . Based on Theorem 23, Example 14 can be further calculated in Example 24.*

*Example 24. *Let , and be two BDHF elements. Then, the distance measure between and is calculated after Example 14 as follows:

*The key characteristic of the distance measure proposed in this paper is to combine membership or nonmembership degrees with their support intensity. Now, if we do not consider support intensity of membership or nonmembership degrees, could different distance measures between BDHF elements be obtained? It can be calculated in Example 24 that without support intensity . By contrast, considering support intensity we can obtain that as mentioned above. Obviously, the results from these two ways are different. Therefore, whether the decision maker considers support intensity of membership or nonmembership degrees may lead to different distance measures. Moreover, in decision making, it is the most important thing for the decision maker to try their best to consider all original information. That is the main reason why support intensity is rational and necessary for the decision making.*

*After obtaining the generalized distance measure between two BDHF elements, the generalized distance measure between two BDHF sets could also be defined in the following.*

*Definition 25. *Let , and be two BDHF sets and weights for each BDHF element, respectively. Then, the generalized distance between and is measured by where is calculated by Definition 13.

*Similar to the generalized distance measure in Definition 13, the generalized distance measure in Definition 25 has the same properties as follows.*

*Theorem 26. Suppose that , and are two BDHF sets and weights for each BDHF element, respectively. The generalized distances measured by Definition 25 satisfy the following:(1)Boundedness is .(2)Commutativity is .(3)Conditional reflexivity is if , , and .*

*Theorem 26 can be directly deduced from Theorem 18 and thus its proof is omitted.*

*4. Developed VIKOR Method with BDHF Information*

*4. Developed VIKOR Method with BDHF Information*

*In this section, we introduce the proposed method, mainly including the modeling of MADA problems under BDHF environment, determination of attribute weights, and the process of extended VIKOR method.*

*4.1. Modeling of MADA Problems with BDHF Information*

*4.1. Modeling of MADA Problems with BDHF Information*

*Differing from conventional MADA approaches, fuzzy decision matrix with BDHF assessments is constructed in this section.*

*Suppose that a MADA problem includes alternatives and attributes The relative weights of attributes are represented by such that and , where the notation “” denotes “transpose.” Let the BDHF assessment of alternative on attribute be symbolized by . Given , ; and such that , , , , , and , then a BDHF decision matrix can be profiled by*

*It can be known from Definition 7 that each element in is a BDHF element, so can be regarded as a matrix of BDHF elements.*

*4.2. Determination of Attribute Weights*

*4.2. Determination of Attribute Weights*

*Weight, as a useful technique for reflecting relative importance of objectives, has been widely applied in MADA. To date, a lot of methods for determining weights are proposed such as AHP, maximizing deviation method, the CRITIC (criteria importance through intercriteria correlation) method [32], the standard deviation method [32], and especially entropy method which has been extensively used in fuzzy set. Motivated by AIF entropy measure, we define a new entropy measure with BDHF information.*

*Definition 27. *Let , and be a BDHF decision matrix and attribute weights for a MADA problem, respectively. Then, entropy measure with BDHF information is defined as follows:where and symbolize the numbers of possible membership and nonmembership degrees, respectively.

*Through observing the features of entropy measure in Definition 27, it can be inferred that entropy measure could be considered a compound function with respect to possible membership degree and possible nonmembership degree . In order to obtain axiomatic conditions of the entropy measure, a rule about the mentioned compound function in Theorem 28 is firstly demonstrated.*

*Theorem 28. Given a function , where , it satisfies that (1)when , is increasing with respect to and decreasing for ;(2)when , is increasing with respect to and decreasing for .*

*Theorem 28 is proven in Section A.4 of Appendix A.*

*Based on Definition 27 and Theorem 28, it can be verified that the BDHF entropy measure satisfies the following axiomatic conditions.*

*Theorem 29. A real function is called a BDHF entropy if satisfies the following axiomatic requirements:(1) if each BDHF set (, nonfuzzy).(2) if for all , , .(3) if, when and , or .(4)*

*Theorem 29 is proven in Section A.5 of Appendix A with the help of Theorem 28.*

*After obtaining the new entropy measure, the weight of attribute for alternative is determined by where , = 1, and can be calculated by (24).*

*According to entropy theory, the smaller the entropy value for each attribute is, the more the useful information the decision maker can acquire. Therefore, the attribute should be assigned a bigger weight and vice versa.*

*4.3. Procedure of the Developed VIKOR Method*

*4.3. Procedure of the Developed VIKOR Method**VIKOR method is used to find the compromise solution which is the closest to the ideal solution, and a compromise means an agreement established by mutual concessions [14, 15]. So far, it has been widely used in solving decision making with conflicting and noncommensurable attributes in MADA. Kim and Chung proposed a fuzzy VIKOR approach to assess the vulnerability of the water supply to climate change and variability in South Korea [33]. Under interval type 2 fuzzy environment, Qin et al. proposed an extended VIKOR method based on prospect theory for multiple attribute decision making [12]. Based on HF set, an extended VIKOR method is developed by Zhang and Wei to solve multiple attribute decision making problems [34]. It can be deduced from the mentioned references that there are three potential hypotheses in fuzzy VIKOR method for solving MADA problems: it is difficult to express the preference of a decision maker exactly; there are conflicting and noncommensurable attributes in MADA; and decision makers can accept compromise solutions.*

*Then, the procedure of the VIKOR method in BDHF context to deal with MADA problems is shown in Figure 1, which will be elaborated step by step.*