1. Introduction
In real environment, a successful decision-making often requires consideration of multiple factors (criteria). This kind of problem related to decision-making simultaneously involving multiple criteria is called multi-criteria decision-making (MCDM) problem [
1]. Since Zadeh put forward the theory of the fuzzy sets (FSs) in 1965 [
2], MCDM based on FSs theory has been widely developed and applied to practical decision-making problems [
3,
4,
5,
6,
7,
8,
9,
10,
11]. Due to the inherent fuzziness of human preference information, a single membership degree of FSs cannot properly describe the fuzziness and uncertainty in the decision-making process. After that, Atanassov [
12] defined intuitionistic fuzzy sets (IFSs), including a membership, non-membership, and hesitation index, as the extension of FSs [
2]. However, FSs and IFSs cannot deal with indeterminate information. Thus, Smarandache et al. [
13,
14] developed neutrosophic sets (NSs), involving truth membership, indeterminacy membership, and falsity membership, respectively, and it lies in the range of
[
15]. Obviously, it is the extension of the standard interval
of IFSs. Subsequently, a single-valued neutrosophic set (SVNS) was proposed, that is an instance of NS [
16,
17,
18,
19,
20]. In addition, other extensions of NSs, including interval neutrosophic sets [
21], neutrosophic cubic sets [
22,
23], single-valued neutrosophic hesitant fuzzy sets (SVNHFSs) [
24], rough neutrosophic sets (RNSs) [
25], interval rough neutrosophic sets (IRNSs) [
26], probability multi-valued neutrosophic sets [
27,
28], and other extensions [
29,
30], were proposed and applied to solve theoretical problems.
Additionally, SVNS, as a popular method to describe DMs’ preference information, has greatly received scholars’ attention, and also was studied from different aspects, such as aggregation operators [
31,
32,
33,
34,
35,
36], outranking relations [
37], and information measures [
38,
39]. For instance, Liu and Wang [
31] presented a single-valued neutrosophic normalized weighted Bonferroni mean operator; Garg [
36] presented single-valued neutrosophic Frank operators; Wu et al. [
39] defined a simplified neutrosophic prioritized aggregation operator. Liu et al. [
28] defined some single-valued neutrosophic Schweizer-Sklar prioritized aggregation operators. To our knowledge, aggregation operators play a significant role in solving MCDM problems. Different aggregation operators are mainly involved in different functions, which can reduce the effect of abnormal data provided by DMs. Especially, power aggregation (PA) operator, defined by Yager [
40], can aggregate the information by using a weighted vector based on support degree among different arguments and allow the evaluation values to be supported.
In practice, we always experience some decision-making problems with the correlation between criteria. For example, tourism attraction selection, constraints of tourists, and preferences of tourists are correlated to each other, and male tourists prefer adventurous tourism attractions. Apparently, there is a redundancy between constraints and preferences, where the sum of the weights of constraints and preferences is greater than the weight of the combination s of two criteria.
The Shapley fuzzy measure and Choquet integral [
41,
42,
43,
44] are highly applied to deal with MCDM problems where the criteria are correlated [
45,
46]. For instance, Zhang et al. [
44] presented some hesitant fuzzy linguistic Shapley Choquet integral operators; Meng et al. [
47] developed interval-valued intuitionistic fuzzy Shapley Choquet integral operators; Qu et al. [
48] defined dual hesitant fuzzy Shapley Choquet integral operators; Nie et al. [
49] developed some Pythagorean fuzzy partitioned normalized weighted Bonferroni mean operator based on Shapley fuzzy measures.
From the above analysis, two shortcomings can be concluded as follows: (1) the existing single-valued neutrosophic aggregation operators only take the importance of assessment values or that of ordered position into account. However, criteria were often interdependent or interactive in the decision-making process; (2) Most of existing methods cannot handle some special MCDM problems where the weight information is incompletely known. Moreover, power aggregation operator can reduce the effects of abnormal assessment values, and Shapley fuzzy measures can simultaneously consider the importance and overall correlation among the criteria. To do this, the main contributions can be summarized as: (1) This paper proposes two new aggregation operators, namely the generalized weighted single-valued neutrosophic power Shapley Choquet average (GWSVNPSCA) operator and the generalized weighted single-valued neutrosophic power Shapley Choquet geometric (GWSVNPSCG) operator, which can avoid the first drawback. (2) This paper develops a MCDM approach based on proposed aggregation operators to solve single-valued neutrosophic problems with incomplete weight information, which can overcome the second drawback.
The rest of the study is constructed as follows. In
Section 2, some related definitions are introduced. Then, the GWSVNPSCA and GWSVNPSCG operators are defined in
Section 3. Next, the single-valued MCDM method accompanied with unknown weight information is constructed in
Section 4. In
Section 5, the selection of tourism attraction is provided to assess the effectiveness of the proposed method. Finally, we summarize the achieved results in
Section 6.
2. Preliminaries
Here, some basic definitions, including Shapley fuzzy measure, PA operator, NSs, and SVNS, are described.
2.1. Shapley Fuzzy Measure
Definition 1 [
42,
43]
. Let be a finite set and be the power set of . Then the function is defined as a fuzzy measure, satisfying:- (1)
and;
- (2)
and, then.
To measure the influence of each condition in a game, Shapley [
42] defined the Shapley function as follows:
Here
and
denote the cardinalities of
and
, respectively. As discussed in Zhang et al. [
44], we have
and
, which can be true. Then,
is called Shapley fuzzy measure [
44]. Moreover, Shapley fuzzy measures, which will be utilized in latter analysis, are additive fuzzy measures.
2.2. PA Operator
The PA operator was developed by Yager [
40] in the form of nonlinear weighted average aggregation operator.
Definition 2 [
40]
. The PA operator is given as:where includes positive real numbers. and denote the support degree for from . After that, the support degree satisfies the properties as follows:- (1)
;
- (2)
;
- (3)
.
2.3. NSs and SVNSs
Definition 3 [
13,
14,
50]
. A NS in is characterized as: . Here , , and denote truth-membership, indeterminacy-membership and falsity-membership respectively. Furthermore, , , and are subsets of , that is, , , and to satisfy the condition required for .
Since NSs can difficultly handle practical problems because of their nonstandard intervals, Ye [
16] defined SVNSs based on standard intervals and developed the corresponding operations for SVNSs.
Definition 4 [
16]
. An SVNS in is defined as: . Here , , and are subsets in the standard interval of [0,1], i.e., , , and .
In particular, if has only one element, then is called a single-valued neutrosophic number (SVNN). For convenience, an SVNN is denoted by .
Definition 5 [
16]
. Let , and be three SVNNs, and with , the following operations can be defined:- (1)
;
- (2)
;
- (3)
;
- (4)
.
However, the operations are unreasonable as previously outlined [
32]. Then, Peng et al. [
32] developed the improved operations of SVNNs and the corresponding comparison method.
Definition 6 [
32]
. Let , and be three SVNNs, and . The SVNNs operations are defined in the following:- (1)
;
- (2)
;
- (3)
;
- (4)
.
Example 1. Let,, andbe three SVNNs, and. Based on the operations presented in Definition 6, we can get the following results:
- (1)
;
- (2)
;
- (3)
;
- (4)
.
Definition 7 [
32]
. Let and be two SVNNs. Then the method of comparison is defined as:- (1)
If, thenispreferableto,representedby;
- (2)
Ifand, thenis preferable to, represented by;
- (3)
If,and, thenis preferable to, represented by;
- (4)
If,and, thenis indifferent to, represented by.
- (5)
where,anddenote the score function, accuracy function and certainty function of SVNNs, respectively.
Example 2. Letandbe two SVNNs, then we haveand. Since, sois preferable to, i.e.,.
Definition 8. Letandbe two SVNNs. The generalized normalized single-valued neutrosophic distance between two SVNNs ofandcan be defined as: Especially, if, thenmay reduce to the normalized single-valued neutrosophic Hamming distance, i.e., If, thenmay reduce to the normalized single-valued neutrosophic Euclidean distance, i.e., Example 3. Based on Example 2, and let, then we have.
3. Generalized Weighted Single-Valued Neutrosophic Power Shapley Choquet Operators
Based on the PA operator and Shapley fuzzy measure, the GWSVNPSCA operator and GWSVNPSCG operator are defined respectively, and the corresponding properties are discussed as well.
3.1. Generalized Weighted Single-Valued Neutrosophic Power Shapley Choquet Averaging Operator
Definition 9. Letbe a group of SVNNs, andbe a Shapley fuzzy measure. Then, GWSVNPSCA operator with dimensionis a mapping GWSVNPSCA:, and Here,,is a permutation of, while it can be presented as,,, and. Moreover,, andpresents the support forfrom, that satisfies the conditions:
- (1)
;
- (2)
;
- (3)
, here d is the distance measure as defined in Definition 8.
Theorem 1. Letbe a group of SVNNs andbe the Shapley fuzzy measure. Then the aggregated results by utilizing the GWSVNPSCA operator is also an SVNN, i.e., Here,and satisfies the conditions mentioned in Definition 9.
Proof. To simplify the process, let in the following proof.
By using the mathematical induction method, if
, based on the operation laws in Definition 6, we have:
Apparently, if , then Equation (7) holds.
If
, Equation (7) holds, i.e.,
and
Then for
, we have
Thus, if , Equation (7) is held. In the other words, for any positive real number , Equation (7) is held. □
Example 4. Letandbe two SVNNs, then we haveand, i.e.,and. Assume,,, and, then, and. Based on the single-valued neutrosophic normalized Hamming distance presented in Definition 8, we can get. Thus, let, from Theorem 1, we have: In the following, a number of properties of GWSVNPSCA operator are discussed.
Theorem 2 (Idempotency). Let be a group of SVNNs. If , then .
Proof. Since
, thus we have
Thus, can be true. □
Theorem 3 (Permutability)
. Let be a group of SVNNs. If accompanies with any permutation of , then, Proof. Since
is an any permutation of
, therefore
, i.e.,
,
and
. Thus,
□
Theorem 4 (Boundedness). Let be a group of SVNNs. If and , then .
Proof. For simplicity, let in the following proof.
Since , i.e., ,
Then
Moreover,
Similarly, .
Thus, we have
i.e.,
.
Hence, we can obtain . □
Theorem 5 (Monotonicity)
. Let and be two groups of SVNNs. If and for all , then Proof. According to Theorem 4, Theorem 5 can be confirmed. Therefore, the process of treatment is omitted here. □
Besides, GWSVNPSCA operator, which defined by combing the advantages of Shapley fuzzy measure and PA aggregation operator, can reduce the effects of abnormal data and simultaneously consider an interrelationship among data and criteria. It is more appropriate in aggregation data because of different parameter.
3.2. Generalized Weighted Single-Valued Neutrosophic Power Shapley Choquet Geometric Operator
Definition 10. Letbe a group of SVNNs, andbe the Shapley fuzzy measure. Then GWSVNPSCG operator of dimensionis a mapping GWSVNPSCG:, andwhere,is a permutation ofsatisfying,and,.
Theorem 6. Letbe a group of SVNNs, andbe the Shapley fuzzy measure. Next, the aggregated results by utilizing GWSVNPSCG operator are also an SVNN, i.e., Proof. The proof is omitted here. □
Example 5. Based on Example 4 and Theorem 6, the following results can be obtained: Similarly, GWSVNPSCG operator has the following properties.
Theorem 7 (Idempotency). Let be a group of SVNNs. If , then .
Theorem 8 (Permutability)
. Let be a group of SVNNs. If is any permutation of , then, Theorem 9 (Boundedness). Let be a group of SVNNs. If and , thus, .
Theorem 10 (Monotonicity)
. Let and be two groups of SVNNs. If and for all , then 4. A Single-Valued Neutrosophic MCDM Approach with Incomplete Weight Information
Assume
is a group of alternatives and
includes corresponding criteria.
is the single-valued neutrosophic decision matrix, and
can be provided by the DM with respect to
for criterion
being expressed by SVNNs. If the weight of criteria for the Shapley fuzzy measure would be known, then the corresponding aggregation operators can be directly used to obtain the aggregated values; otherwise, if it would be partly known or fully unknown, next, the weights of criteria should be initially determined. The scheme of proposed method can be presented in
Figure 1, and the procedure aiming to determine the optimal alternative(s) is provided in the following.
Phase 1. Construction and normalization of the decision matrix
In this phase, the criteria for each alternative are assessed by DMs. The decision-matrix can be constructed accordingly. Moreover, the criteria always involves benefit type and cost type in MCDM problems. If the criteria are benefit-based, then, there is no need to normalize the decision matrix; otherwise, the cost-based criteria should be transformed into corresponding benefit-based criteria as:
where,
is the complement of
.
Then, the normalized decision matrix can be obtained.
Phase 2. Determinations of the Shapley fuzzy measures
Step 2.1. Determination of ideal solutions
Let be positive ideal solution, and be negative ideal solution, respectively. Here, and .
Step 2.2. Calculation of closeness coefficients
Based on the technique presented for order preference by similarity to ideal solution (TOPSIS) method [
51], the closeness coefficient of candidate from positive ideal solution can be calculated as follows:
where,
can be obtained by using Equation (3).
Step 2.3. Determination of Shapley fuzzy measures
According to TOPSIS method [
52], the smaller
, the better
is. If the weight information of criteria would be partly known, then, an optimal model based on the Shapley fuzzy measure can be constructed as:
where,
denotes the integral weight of the criterion
, and
represents the weight information.
Next, fuzzy measure and corresponding the Shapley fuzzy measure can be obtained by solving the mode (12).
Phase 3. Aggregation the preference information
Step 3.1. Determination of the supports
From Definition 9, we can achieve the supports
as:
where,
represents the support for
from
, satisfying the conditions provided in Definition 9. Besides,
can be calculated by using the distance presented in Definition 8.
Step 3.2. Determination the weighted supports
The weighted support
of
from
can be calculated using the Shapley fuzzy measure of the criterion
.
Step 3.3. Determination of the weights
From Step 3.2, we can determine the weights
associated with
as:
Here and .
Step 3.4. Calculation of the global values
By using GWSVNPSCW operator, i.e., Equation (8), the global value of candidate can be obtained.
Step 3.5. Calculation of the values of score, accuracy, and certainty
Based on Definition 7, the values of score , accuracy , and certainty of () can be achieved.
Step 3.6. Ranking the alternatives
According to Step 3.5, all candidates can be ranked and the optimal one can be selected.
5. Tourism Attraction Selection
In this section, a MCDM problem under single-valued environment is presented to illustrate the efficacy of the proposed method by selecting an appropriate tourism attraction. With the widespread popularity of the mobile Internet and the increasing demand of tourists regarding the quality of tourism services, online tourism, mobile tourism, and other services have gradually risen. Personalized tourism recommendations can provide tourism products for a user, reflecting his/her needs and preferences and help him/her promptly make tourism decisions. In the personalized tourism recommendation system, accurate and effective recommendations are provided mainly through four criteria related to preference information, including constraints, tourism resource bank, user’s tourism demand, and user’s preference for tourism products.
: Constraints are described as some objective conditions that affect the user’s decision making about tourism, including the age or physical condition of user, the gender or income of user, and weather conditions related to tourist attractions, carrying children and the elderly, etc.
: The tourist resource bank contains six aspects of the tourist products, including food, residence, tourism, entertainment, and purchase. It also contains the data related to various kinds of tourism products. The tourist resource bank is of great importance to analyze, produce, and make up the recommended results. Generally speaking, tourist attractions’ recommendation can collect the names of scenic spots and tickets, categories of scenic spots, grades, longitude and latitude directions, and so on.
: Tourism demand refers to the user’s demand for tourism products that they would like to purchase, that is, a subjective condition, such as the user’s tourism days, hotel’s condition, etc.
: The user’s preference for tourism products can be obtained by analyzing the tourist’s historical tourism data (such as the tourist photos uploaded by the user, the user’s comments or rating on the tourism products), the pages on the tourism website, purchase or transaction records of tourism products, etc.
According to the four criteria presented above, users should select the best tourist attraction according to their own and actual situation of the tourist attractions. Apparently, four criteria are correlated with each other. Suppose five tourist attractions (candidates) are taken into consideration, which are represented by
. During assessment, four criteria, namely:
: constraints;
: the tourist resource bank;
: tourism demand;
: preferences are considered. The corresponding weights of these four criteria are partly known, given as
. The evaluation of five candidates
is performed using SVNNs by the DM based on criterion
. Then, the single-valued neutrosophic decision matrix
is established and shown in
Table 1.
5.1. The Decision-Making Process
The decision-making process, by using the proposed method, is as follows.
Phase 1. Construction and normalization of the decision matrix
Since the assessment values are provided by DMs in form of SVNNs and the criteria are benefit-based, as a result, the normalized decision matrix is obtained.
Phase 2. Determination of Shapley fuzzy measures
Step 2.1. Determination of ideal solutions
From
Table 1, we can achieve positive ideal solution
and negative ideal solution
, as displayed in
Table 2.
Step 2.2. Calculation of the closeness coefficient
Let
, the closeness coefficient of alternative from positive ideal solution can be determined as given in
Table 3.
Step 2.3. Determination of the Shapley fuzzy measures
Then the optimal Shapley fuzzy measure model on the basis of criteria can be constructed as:
With the help of MATLAB software, the mathematical programming model presented above can be solved, and the fuzzy measure on the basis of the criteria is
,
Form Definition 1, the corresponding Shapley fuzzy measure can be calculated.
Phase 3. Aggregation of the preference information
Step 3.1. Determination of the supports
From Definition 9, we can achieve the supports
as follows:
Step 3.2. Determination of the weighted supports
The weighted support of each assessment value could be obtained, as shown in
Table 4.
Step 3.3. Determination of the weights
Next, the weights
associated with the
on the basis of the criterion
could be achieved, as presented in
Table 5.
Step 3.4. Calculation of the global values
By using GWSVNPSCW operator and
, the global assessment value
of candidate
can be obtained as:
Step 3.5. Calculation of the values of score, accuracy, and certainty
According to Definition 7, the values of score
can be calculated as follows:
Since the values of score are different, thus there is no need to calculate the values of accuracy and certainty.
Step 3.6. Ranking the candidates
Apparently, , thus, we have . The optimal attraction is while the worst one is .
If the GWSVNPSCG operator is used in Step 3.4 to aggregate the preference information of each candidates, then, the final ranking is . The best attraction is as well.
5.2. Sensitivity Analysis
In order to discuss the influence of different values
and
on the final ranking, sensitivity analysis is carried out. If GWSVNPSCW and GWSVNPSCG operators are used respectively in the Step 3.4 and
, then the results of the two cases are shown in
Table 6 and
Table 7 and
Figure 2,
Figure 3,
Figure 4,
Figure 5 and
Figure 6.
For GWSVNPSCW operator, if
, accordingly, the final ranking is
; however, if
, the final ranking is
, as shown in
Table 6. Although the position of
and
is different as two parameters changes, the optimal attraction is always
, while the worst one is
. Moreover, from the score values presented in
Table 6, it can be seen that the difference between the first position and the second position is greater as two parameters change, demonstrating the rationality of the alternative
as an optimal scheme. For GWSVNPSCG operator, if
, therefore, the final ranking is
; if
, as a result, the final ranking is
; however, if
, thus, the final ranking is
, as shown in
Table 7. Although the position of
, and
is different, the optimal attraction is
. Besides, in order to further understand the influence of parameters on final rankings, the trend of score values of five candidates are presented with two parameters in the range of
by using GWSVNPSCW and GWSVNPSCG operators, as shown in
Figure 1,
Figure 2,
Figure 3,
Figure 4 and
Figure 5. It can be seen that the fluctuation tendency of score values, as displayed in
Figure 3, indicates that the candidate
is always the best one.
5.3. Comparative Analysis
In order to examine the effectiveness of the developed method, results achieved by using GWSVNPSCA operator are compared to a number of existing methods based on aggregation operators [
16,
31,
35,
36,
39,
52]. Since the majority of available methods cannot truly resolve situations where the weight information is partly known, the weight is determined as
for the comparative analysis.
For the proposed method, the determined weights could be utilized to aggregate preference information in Phase 3 and
, For the method based on prioritized operator [
39], we assume that the prioritization of the criteria satisfies
. For the methods based on Bonferroni mean [
31], Frank operator [
36], and Hamacher operator [
52], the corresponding parameters are determined as
and
, respectively. Then, the results could be obtained as shown in
Figure 7.
According to the results presented in
Figure 7, we can conclude the following achievements. Firstly, the final ranking by using the developed method is the same as those previously presented methods [
31], and the final order is
. Moreover, the developed method includes PA operator that can highly reduce the effects of abnormal assessment values. Secondly, although the positions of
,
and
based on the proposed method are different from other previously reported methods [
35,
36,
39,
52]. the optimal alternative is always
, Finally, the result based on algebraic operator [
16] is
, which is not consistent with other methods. The main reason for this discrepancy is that the rules of corresponding operation are unreasonable as previously discussed [
35].
5.4. Managerial Implications
In this study, an MCDM method based on the single-valued neutrosophic aggregation operators is proposed to handle tourism attraction selection problems. Moreover, this study investigates a sensitivity analysis and comparison analysis to prove the validity of the developed method. The results indicated that is the optimal one. The management implications of the developed method can be concluded in the following. First, the evaluation criteria of tourism attraction selection consist of constraints, tourism resource bank, user’s tourism demand, and user’s preference for tourism products, which can meet the requirements of personalized tourism recommendation. Second, DMs can express their preference information from three perspectives, i.e., truth, indeterminacy, and falsity, which can precisely describe the uncertain information. Third, the proposed aggregation operators consider the interrelationship among criteria, which can make the final results more in accordance with the actual situation. For example, the constraints c1, tourism demand c3, and tourism preference c4 are correlated with each other in the real decision-making environment. If the correlation cannot be considered in the decision-making process, then the accuracy of recommendations will be attenuated to some extent. Last, it is difficult for DMs to provide the weight information of criteria in the form of crisp values directly. Thus, the proposed method with incompletely weight information has important theoretical significance for managers to improve the accuracy of recommendations.
6. Conclusions
In this study, a single-valued neutrosophic MCDM problem with interdependent characteristics is investigated. Firstly, according to the power aggregation operator and Shapley fuzzy measure, the GWSVNPSCA and GWSVNPSCG operators are accordingly defined, and the corresponding special cases are discussed as well. Secondly, based on the developed aggregation operators, an integrated MCDM approach is proposed to effectively solve single-valued neutrosophic problems where the weights of the criteria were incompletely known. A mathematical programming model based on fuzzy measure is established to obtain the optimal Shapley fuzzy measure. Then, the developed operators are used to aggregate the preference information. Eventually, a theoretical example is presented to testify the effectiveness of the developed approach, in which it is revealed that the results are reasonable and credible. The main advantages of this research can be concluded in two aspects. On the one hand, the developed aggregation operators can take the interrelationship among criteria into account and also simultaneously reduce the effects of abnormal assessment values. On the other hand, the proposed MCDM methods can solve single-valued neutrosophic problems where the weight information is incompletely known or completely known. The limitation of this paper is that it cannot consider the multiple DMs in the decision-making process. In the future, the other fuzzy measures of SVNNs and their corresponding group decision-making methods should be further investigated.