This section is divided into two subsections. One presents the improved operations laws for the T-SFSs, while other presents some improved geometric AOs under the T-SFS environment.
3.1. Improved Operational Laws
In this section, we present some new, improved operations laws by incorporating the features of the degree of refusal into the analysis.
Definition 9. Letandbe two T-SFNs. Then, the proposed operational laws are defined as
- (1)
- (2)
For two T-SFNs, and , new operations of multiplication can be construed from four aspects, such as between:
- (1)
Two non-membership functions of different T-SFNs.
- (2)
Two membership functions of different T-SFNs.
- (3)
Membership and non-membership functions of different T-SFNs.
- (4)
Two neutral functions of different T-SFNs.
These multiplication rules are of the form:
. Therefore,
is considered as a probability non-membership (PN) function operator, that is,
. Therefore,
is considered as a probability membership (PM) function operator, that is,
is considered as a probability heterogeneous (PH) function operator, that is,
. Therefore,
is considered as a probability neutral (PNe) function operator, that is,
From the proposed laws, it is observed that the several existing laws can be considered as a special case of it. For instance,
- (i)
For , above operations become valid for SFNs.
- (ii)
For , above operations become valid for PFNs.
- (iii)
For and , above operations become valid for PyFNs.
- (iv)
For and , above operations become valid for IFNs.
Further, it is observed that for the above defined PN, PH satisfies the following properties:
Theorem 1. Letandbe four T-SFNs. Then, we have:
- (1)
Boundedness:.
- (2)
Monotonicity: Ifand. Then.
- (3)
Commutativity:.
Proof. (1) For two T-SFNs, P and Q, and by definition of PN, we have Thus, we have PN(1,1) = 1 and PN(0,0) = 0. Further, since and , which implies that . Also, . Therefore, .
(2) Since and . Thus, for any , we get and , and hence . Thus, holds.
(3) Holds trivial. □
Theorem 2. Letandbe four T-SFN. Then:
- (1)
Boundedness:.
- (2)
Monotonicity: If. Thenand if. Then
- (3)
Commutativity:.
Proof. Similar to Theorem 1, so we omit here.
Theorem 3. If P and Q are two T-SFNs and λ > 0 is a real number, then are also T-SFNs.
Proof. Follows from the definition easily, so we omit here.
Theorem 4. Let,be a T-SFNs,be real numbers. Then we have
- (1)
- (2)
- (3)
.
Proof. Follows from the definition easily, so we omit here.
3.2. Aggregation Operators
In this section, based on the above proposed operational laws, we have proposed some series of geometric interactive improved AOs, namely, T-SFWGIA, T-SFOWGIA, and T-SFHGIA, under the T-SFS environment.
Definition 10. For any collection,of T-SFNs. If the mappingthenis called a T-Spherical fuzzy weighted geometric interactive averaging (T-SFWGIA) operator, whereis the weighting vector ofwithand. Theorem 5. For any collection of T-SFNs,, the aggregated values obtained by using Definition 10 is still T-SFNs and is given by: Proof. For any collection of T-SFNs, , we shall proof the result by induction on k.
Thus, hold for
. Now, the result holds for
:
Then for
, we have:
So, the result holds for . Therefore, by the principle of mathematical induction, the result holds for all . □
Theorem 6. If,are T-SFNs. Then the aggregated value using the T-SFWGIA operator is also T-SFN.
Proof. Since
is a T-SFN,
, we have
. So
and
. Then:
Thus, is T-SFN.
Further, it is observed that the proposed operator satisfies certain properties, which are listed as follows: □
Theorem 7. If all T-SFNs,, are equal to, whereis another T-SFN, then Proof. Assume that
is a T-SFN
. Then, by definition of T-SFWGIA operator, we have:
Theorem 8. Ifis a T-SFN and Proof is straightforward.
Theorem 9. For a collection of two different T-SFNs,and, which satisfy the following inequalities ifand, then we have Proof. Since
, we have:
and
As,
we have:
Definition 11. [
34]
For any collection, of T-SFNs. The is a mapping defined as where is the collection of all T-SFNs, then is called a T-SFOWGA operator with weighting vector of with and . Definition 12. For any collection,of T-SFNs. Theis a mapping defined as:thenis called T-SFOWGIA operator, whereis the weighting vector ofwithandand σ is the permutation of {1, 2, …,
k}
, such that σ(
j − 1) ≥
σ(
j)
. Theorem 10. For any collectionof T-SFNs. Then Proof is similar to Theorem 5.
Theorem 11. Ifis a T-SFN,. Then the aggregated value using the T-SFOWGIA operator is also T-SFN.
Proof. Since
is a T-SFN,
, we have
. So
and
. Then:
Thus, is T-SFN. □
Theorem 12. if is a T-SFN .
Theorem 13. Ifis a T-SFN and Proof is straightforward.
Theorem 14. ifis any permutation ofwhere.
Proof. If is any permutation of then we have . Thus, . □
Definition 13. For any collection,of T-SFNs. If the mappingthenis called a T-SFHGA operator, whereandis the weighting vector ofwithand. Theorem 15. [
34]
For any collection, of T-SFNs. If then is called a T-SFHGA operator with weighting vector of with and . Definition 14. For any collection,of T-SFNs. If the mappingthenis called a T-SFHGIA operator, whereis the weighting vector ofwithand. Theorem 16. For any collection,of T-SFNs. Then The following example demonstrates these aggregation operators:
Example 1. Let,,,andare T-SFN. The weight vector foris. With loss of generality, we usefor all calculations.
Firstly, we utilized T-SFHGIA operators on this data to aggregate it.
The score values corresponding to these aggregated numbers were obtained as . Based on the score values, we had the following arrangement of data:
,
,
By using the normal distribution-based method, we found
and by the definition of T-SFHGIA operator we had
Theorem 17. Ifis a T-SFN, then the aggregated value using the T-SFHGIA operator is also T-SFN.
Proof is similar as in Theorem 11.
Theorem 18. ifis a T-SFN.
Proof is similar as in Theorem 12.
Theorem 19. Ifis a T-SFN and Proof is straightforward.
Theorem 20. ifis any permutation ofwhere.
Proof is similar as Theorem 14.
Whenever membership and neutral number of one T-SFN become zero then the membership and abstinence value is not accounted for in the aggregation [
34]. However, the geometric interaction averaging operators that are developed in our manuscript overcome this problem. The example below will describe this more clearly.
Example 2. Letandare T-SFN. The weight vector foris.
For the solution, first we will find the T-SFHGA operator.
As, but
Similarly,
and
satisfy the condition for
.
Scores values for these aggregated numbers were obtained as , and, based on these score values, we had
, ,
By using the normal distribution-based method, we found
, and, by the definition of T-SFHGA operator, we found
This type of aggregated value seems meaningless, as whenever the membership and abstinence value is zero in any one of the T-SFN it will make the value of the membership and non-membership as zero in the whole aggregated value. This shows that the geometric aggregation operator of T-SFSs [
34] does not possess the ability to aggregate such types of information effectively.
On the other hand, the proposed new geometric interactive aggregation operators can process any type of information effectively. Now, the Example 2 was solved using the proposed new aggregation operators in order to justify its effectiveness. For it, we aggregated the data using the T-SFHGIA operator:
The score values of these numbers were obtained as
, and, based on score values, we had the following arrangement:
Now, by using the definition of the T-SFHGIA operator, we found
Clearly, the aggregated value obtained in Equation (8) was an improvement of the one obtained in Equation (7), as it incorporated the zero values occurring in the membership and abstinence of T-SFNs efficiently. The analysis of Equations (7) and (8) proved the significance of proposed aggregation operators.