In this section, we firstly extend the traditional MSM and propose the PMSM operator to handle this situation in which the input arguments are divided into several parts and there are interrelationships among multiple arguments in each part. Then, we extend the PMSM in q-ROFS and define two q-ROFPMSM operators to deal with the aggregation information in the form of q-ROFNs. Finally, we introduce a q-ROFPPMSM operator and the weighted form of the q-ROFPPMSM operator based on PMSM and PA, which not only take advantage of PMSM, but also reduce the negative influence of unduly high or unduly low evaluating values of attributes on the decision result.
4.1. PMSM Operator
In many practical MAGDM problems, we may encounter a situation where the input arguments can be divided into several classes and there are interrelationships among multiple arguments in each class, whereas the attributes in different classes are not related. These situations can be mathematically depicted as follows:
Let be a collection of nonnegative real numbers that are corresponding to the performance value of each attribute, respectively. On the basis of the aforementioned interrelationship pattern, suppose that the arguments are divided into d different classes , satisfying and . Furthermore, suppose that there is an interrelationship among any kh arguments in each class and there is no relationship among arguments of classes Pi and Pj. Then the partitioned Maclaurin symmetric mean (PMSM) operator, which can aggregate the input arguments with above relationship structure, is defined as follows:
Definition 7. Let be a collection of nonnegative real numbers, which are divided into different classes . For the parameter vector with and the being the cardinality of , ifthen the is called the partitioned Maclaurin symmetric mean (PMSM) operator, where traverses all the kh-tuple combination of and the is the binomial coefficient satisfying following formula: From Equation (6), we can know that the PMSM firstly models the interrelationship of attributes belonged to class and provides the satisfaction degree of interrelated attributes of each class by the expression , it is noted that the PMSM can model this case where the relationship type of attributes belonged to class and are different by setting different values for parameter and . Then, the gives the average satisfaction degree of all attributes, which are belonging to class . Therefore, the PMSM is a more reasonable method to solve this situation, where the arguments are divided into several classes and there are interrelationships among multiple arguments in each class.
For the sake of illustrating the calculation procedure of the PMSM operator, a numerical example is provided and depicted as follows:
Example 2. Let represent a collection of attributes, which are divided into two classes and according to the attribute characteristic. Moreover, assume that each attribute is interrelated to any other two attributes in class and each attribute in class is interrelated to each other, that is to say, the parameter and . The actual value of arguments corresponding to the attributes is as follows: a1= 0.4, a2= 0.7, a3= 0.5, a4= 0.6, a5= 0.3, a6= 0.8 and a7= 0.2.
On the basis of Definition 7, the aggregated result of the arguments in class
P1 is given as follows:
Then, the aggregated result of arguments in class
P2 is
Finally, the degree of satisfaction over all arguments can be obtained
Meanwhile, the MSM operator is used to solve the aforementioned example and the aggregated results under the condition of the parameter
k taking two or three are obtained as follows:
The calculation result obtained by the PMSM is different from the results of the MSM. This difference is a result of the former partitioning the argument set into different classes and considering various relationship types among the arguments in each class, whereas the later only assumes that there is an interrelationship among any k arguments.
Some special cases with respect to the cardinality of class and the parameter vector of the PMSM operator are investigated.
Remark 1. When all arguments belong to same class and the types of the interrelationship among arguments are also the same, namely, the cardinality of and , then the PMSM reduces to the MSM [3] operator as follows: Remark 2. In some practical decision making situations, the attributes can be divided into different classes and the type of relationship structure is consistent in each class , that is to say, and for . Then Equation (6), can be modified as follows: Remark 3. It is noted that the PMSM can be reduced to a special case of the partitioned Bonferroni mean operator [4], with the parameters s and t being equal to one, when the attributes can be divided into different classes and there is an interrelationship between any two attributes in each class , that is to say, for . Remark 4. In some practical decision making situations, it may happen that some attributes have no relationship with any of the rest of the attributes, namely, they do not belong to any classes. In order to solve this case, we can divide the attributes into two sets. Meanwhile, we put these attributes, which are not related to any attributes in a single set denoted by and put other attributes in another set denoted by . Assume that the attributes in are divided based on a previous relationship structure. Equation (6) can be modified as follows: In the following, some properties of PMSM operator are discussed as follows:
Theorem 1 (Idempotency). Let be a collection of nonnegative real numbers. For the parameter vector with and the being the cardinality of , if , then we can get Proof. Based on the assumption that
are equal to
a for all
, then we can get
□
Theorem 2 (Monotonicity). Let and be two collections of nonnegative real numbers. For the parameter vector with and the being the cardinality of , if for all , then Proof. Based on the assumption that
for all
, then we can obtain
□
Theorem 3 (Boundedness). Let be a collection of nonnegative real numbers. For the parameter vector with and the being the cardinality of , if and , then Proof. Based on the Theorem 2, we can obtain
And
Furthermore, based on the Theorem 1, we can obtain
4.2. q-ROFPMSM Operator and q-ROFWPMSM Operator
The PMSM can only deal with evaluation values in the form of nonnegative real numbers, but it is not valid to the information that is expressed by the q-ROFNs. In this section, we shall apply the PMSM operator in q-rung orthopair fuzzy environment and propose the q-rung orthopair fuzzy partitioned Maclaurin symmetric mean (q-ROFPMSM) operator and q-rung orthopair fuzzy weighted partitioned Maclaurin symmetric mean (q-ROFPMSM) operator
Definition 8. Let be a collection of q-ROFNs which are divided into d different classes . For parameter vector with and the being the cardinality of , ifwhere the traverses all the kh-tuple combination of and is the binomial coefficient. Then the is called the q-rung orthopair fuzzy partitioned Maclaurin symmetric mean (q-ROFPMSM) operator. Theorem 4. Let be a collection of q-ROFNs. For the parameter vector with and the being the cardinality of , then the aggregating result obtained by Equation (15) is still a q-ROFN and presented as follows: Considering the influence of the partition number of the argument set and the relationship structure of the argument on q-ROFPMSM, some special cases of the q-ROFPMSM operator are put as the remark below:
Remark 5. When all arguments belong to the same class and the types of the interrelationship among arguments are also the same, that is to say, the number of the class , the cardinality of and the , then the q-ROFPMSM reduces to the q-rung orthopair fuzzy Maclaurin symmetric mean (q-ROFMSM) operator as follow: Remark 6. When there is no partition among argument sets and the types of the interrelationship among arguments are same, namely, the cardinality and the parameter . Under the above conditions, we further investigate some special cases of q-ROFPMSM with parameter k taking some particular values.
Case 1: If
, then Equation (16) reduces to
q-rung orthopair fuzzy average mean (
q-ROFA) operator as follows:
which is a special case of the
q-rung orthopair fuzzy weighted average mean (
q-ROFWA) operator defined by Liu and Wang [
31].
Case 2: If
, then Equation (16) reduces to the
q-rung orthopair fuzzy Bonferroni mean (
q-ROFBM) operator introduced by Liu and Liu [
32].
which is a special case of the
q-ROFBM operator with the parameters
s and
t being equal to 1.
Case 3: If
, then Equation (16) reduces to the
q-rung orthopair fuzzy geometric (
q-ROFG) operator as follows:
which is a special case of the
q-rung orthopair fuzzy weighted geometric (
q-ROFWG) operator proposed by Liu and Wang [
31].
Theorem 5 (Idempotency). Let be a collection of q-ROFNs. For the parameter vector with and the being the cardinality of , if for all , then Theorem 6 (Monotonicity). Let be and two collections of q-ROFNs. For the parameter vector with and the being the cardinality of , if and , then Theorem 7 (Boundedness). Let be a collection of q-ROFNs. For the parameter vector with and the being the cardinality of , if and , then The proof of Theorems 5–7 are provided in
Appendix A.
Note that the argument weights can produce a great impact on aggregated results, so we take into account the importance of the argument itself and propose the q-ROFWPMSM operator to overcome the drawbacks of q-ROFPMSM.
Definition 9. Let be a collection of q-ROFNs which are divided into d different classes . For parameter vector with and the being the cardinality of , ifwhere the traverses all the kh-tuple combination of and is the binomial coefficient. The denotes the weight information of with and . Then the is called the q-rung orthopair fuzzy weighted partitioned Maclaurin symmetric mean (q-ROFPMSM) operator. Theorem 8. Let be a collection of q-ROFNs and denote the weight information of with and . For the parameter vector with and the being the cardinality of , then the aggregating result obtained by Equation (24) is still a q-ROFN and presented as follows: The proof of this theorem is similar to Theorem 4, so it is omitted here.
Meanwhile, it is easily proved that the q-ROFWPMSM satisfies the Monotonicity and Boundedness properties.
Remark 7. When the arguments can be divided into d different class and each member of class is interrelated to each other, namely, for all . Then the q-ROFWPMSM reduces to a special case of q-rung orthopair fuzzy weighted partitioned Bonferroni mean (q-ROFWPBM) operator with the parameters s and t being equal to one. 4.3. q-ROFPPMSM Operator and q-ROFWPPMSM Operator
In a practical decision making process, the decision maker may provide unduly high or unduly low evaluation values for attributes due to the lack of time and the difference of knowledge. The PA can reduce the bad influence of unreasonable argument on aggregation result by calculating the support measure between arguments. Thus, we propose the q-rung orthopair fuzzy power partitioned Maclaurin symmetric mean (q-ROFPPMSM) and the q-rung orthopair fuzzy weighted power partitioned Maclaurin symmetric mean (q-ROFPPMSM) operators that take advantage of PMSM and PA.
Definition 10. Let be a collection of q-ROFNs which are divided into d different classes . For parameter vector with and the being the cardinality of , ifthen the is called the q-rung orthopair fuzzy power partitioned Maclaurin symmetric mean (q-ROFPPMSM) operator, where the traverses all the kh-tuple combination of and is the binomial coefficient. Meanwhile, the and is the support for and which satisfies following properties: - (1)
;
- (2)
;
- (3)
if , the is the distance of q-ROFNs
In order to simplify Equation (27), we define
And
. The
is called as the power weighting vector which satisfies
and
. Therefore Equation (27) can be expressed as follows:
Theorem 9. Let be a collection of q-ROFNs. For the parameter vector with and the being the cardinality of , then the aggregating result obtained by Equation (29) is still a q-ROFN and is presented as follows: The proof of this theorem is similar to Theorem 4, so it is omitted here.
Theorem 10 (Idempotency). Let be a collection of q-ROFNs. For the parameter vector with and the being the cardinality of , if for all , then Theorem 11 (Boundedness). Let be a collection of q-ROFNs. For the parameter vector with and the being the cardinality of , if and , thenwhereand The proof of these theorems is provided in
Appendix B.
In the following, we provide the weighted form of q-ROFPPMSM operator.
Definition 11. Let be a collection of q-ROFNs which are divided into d different class and the represent the cardinality of . The is the weighted vector with and . For the parameter vector r with for all , ifthen the is called the q-rung orthopair fuzzy weighted power partitioned Maclaurin symmetric mean (q-ROFWPPMSM) operator, where the traverses all the kh-tuple combination of and is the binomial coefficient. Meanwhile, the and is the support for and which satisfies following properties: - (1)
;
- (2)
;
- (3)
, the is the distance of q-ROFNs
In order to simplify Equation (33), we define
and
. The
is called as the power weighting vector which satisfies
and
. Therefore Equation (33) can be expressed as follows:
Theorem 12. Let be a collection of q-ROFNs and denote the weight information of with and . For parameter vector with and the being the cardinality of , then the aggregating result obtained by Equation (35) is still a q-ROFN and presented as follows: The proof of the theorem is similar to the Theorem 4, which is omitted here.