1. Introduction
The theory of a fuzzy set (FS) was proposed by Zadeh [
1] in 1965, where he defined the degree of membership (DM) limited to
. FS is a very powerful tool to solve (MAGDM) multi-attribute decision-making and MAGDM problems. FS may not solve some complex problems, for instance, when an individual faces information in the shape of yes or no. To solve that kind of information, Atanassov [
2] explored the theory of an intuitionistic fuzzy set (IFS), which is the expansion of FS to deal with indistinct data in daily life problems. In IFSs,
denotes the DM and
denotes the degree of non-membership (DNM) that makes a pair of the form
such that
. The most important feature of IFS is that the sum of the duplet is less than or equal to 1, i.e.,
. Current work on IFS can be discovered in [
3,
4,
5] to see the impact of IFSs. Occasionally, we take some pair of numbers randomly, such as
, for which
, which exceeds 1. To cope with this kind of issue and to handle such information, Yager [
6] introduced the structure of Pythagorean FS (PyFS). A PyFS permits the sum of the squares of the duplet between
and
, i.e.,
. Hence the pair of numbers
can be classified as a Pythagorean fuzzy number (PyFN) because
. Yager increased the range for assigning the duplet by introducing the notion of PyFS. On the theory of PyFS, some current work may be viewed in [
7,
8,
9,
10]. Similarly, IFS and PyFS also face relevant problems in assigning the duplet independently. Yager [
11] generalized the notion of IFS and PyFS to q-rung orthopair FS (qROFS), in which the sum of the qth-power of the duplet lies between
to
using the variable parameter
, i.e.,
. If we choose information
as DM and
as DNM, we have
. Then, such a duplet cannot be classified as intuitionistic fuzzy or Pythagorean fuzzy but can be considered as a q-rung orthopair fuzzy number (qROFN) by fixing
. Some current work may be viewed in [
12,
13,
14,
15,
16].
To cope with uncertainty or inconsistency, the frame of IFS seems to be a limited version, for example, in the scenario of voting when an expert provides data in the shape of yes, abstinence, no, and refusal. To survive that kind of situation, the principle of a picture fuzzy set (PFS) was presented by Cuong [
17], which deals with three-dimensional information using a degree of abstinence (DA) and degree of refusal (DR), along with DM and DNM. The well-known PFS has a strict condition on the DM, DNM, and DA, which states that the sum of all three must be less than or equal to
. Countless studies on PFSs have been conducted involving a diverse range of applications which can be seen in [
18,
19,
20,
21]. After some time, it was realized that the theory of PFS is not valid in numerous situations as it was difficult to determine accurate information because of strict limitations on the DM, DA, and DNM, for instance, when the information is in the form of
, such as
. Due to this drawback of PFS, Mahmood et al. [
22] introduced the theory of a spherical fuzzy set (SFS) that provides enlargement in the range for assigning the DM, DA, and DNM from
with the condition that
, which is more reliable and flexible than the frame of PFS. The notion of SFS noticeably expanded the space of PFS but still the domain of the SFS is restricted to cope with some kinds of situations. Mahmood et al. [
22] generalized the idea of SFS by introducing the concept of T-spherical fuzzy (TSFS), which was completely flexible for the allocation of the DM, DNM, and DA with no limitation at all. For a triplet
, for which
and
, such triplets cannot be specified in the layout spherical fuzzy or picture fuzzy settings. To make the information of the type
applicable, we have
in the frame of TSFSs, for which
. Therefore, TSFS is the most generalized structure of FS theory that can be applied to various situations. Studies on the aggregation operators (AOs) of TSFSs can be found in [
23,
24,
25,
26,
27,
28], while the study of the information measures of TSFSs may be seen in [
29,
30,
31]. Particular studies on the TSF graphs and TSF soft sets can be seen in [
32,
33].
There exist numerous kinds of AOs to aggregate the data; however, certain AOs or no one interrelates the input information. To find the interrelationship of the input arguments, Yager [
34] developed the power average operator and Liu and Yu [
35] presented some density AOs which consider the density weights of the attributes. To efficiently consider the relationship of the aggregated information, Bonferroni [
36] presented the idea of BMOs and the Heronian mean operator (HMO) introduced by Sykora [
37]. In IFSs, the idea of BMOs was widely studied by Xu and Yager [
38], where DM, DA, and DNM are used to express the BMOs. Liang et al. [
39] enhanced the idea of BMOs by enlarging its range by defining it for Pythagorean fuzzy information. The concept of BMOs was further strengthened by Liu and Liu [
40] by giving them flexibility for allocation. Some BMOs are presented by Ates and Akay [
41], in which DM, DNM, and DA are used along with the frame of PFSs. Regarding BMOs, some beneficial work may be shown in [
42,
43,
44,
45,
46,
47,
48,
49].
Keeping in mind the discussion of the above paragraph, BMOs take account of the interrelationship between the input information with larger flexibility, unlike averaging AOs [
23], Einstein AOs [
27], power AOs [
34], and density AOs [
35], under uncertainty. Moreover, the BMOs based on the duplets of IFSs, PyFSs, qROFSs, and GBMO describe uncertain information using a DM and DNM only and hence information loss is likely to occur [
45,
46,
47,
48,
49]. These structures of IFSs and PyFSs have also a limitation in allocating the duplets due to their strict nature. Furthermore, the BMOs discussed in the frames of PFSs and SFSs [
41,
42,
43,
44] also fail in providing independence for assigning the DM, DNM, and DA under uncertain conditions. Ullah et al. [
50,
51] suggested that expressing the uncertain knowledge by means of an interval instead of crisp numbers leads us to reliable results and proposed the novel notion of IVTSFS. This significance can be seen numerically in [
50]. By keeping all these factors in mind, as well as the broad approach of IVTSFS proposed by Ullah et al. [
50,
51], the aim of this research study is to develop the concepts of BMOs in the layout of IVTSFSs, where the uncertain information is expressed using a DM, DNM, DA, and DR in the form of closed sub-intervals of
, with greater flexibility and hence significantly decreased chances for information loss.
The application of fuzzy MAGDM in the field of energy is eminent and several studies have been established in this regard. For sustainable energy planning, Riaz et al. [
52] used the notion of the Einstein AOs of qROFSs. Dhiman and Deb [
53] used TOPSIS and CORPAS methods to study their applications in hybrid wind farms. Another interesting approach in the field of energies is the site selection of the solar photovoltaic power plant using two-stage decision making by Wang et al. [
54]. Wang et al. [
55] also studied the performance evaluation of the solar photovoltaic plants using three-stage decision-making algorithms. Riaz et al. studied the plastic recycling phenomena using cubic bipolar fuzzy information. The problem of the workplace charging station is comprehensively discussed by Erdogan et al. [
56]. Our goal of the presented BM operators is to apply them in MAGDM problems in the field of solar energy, where the selection of the most reliable solar cells is carried out using a comprehensive numerical example.
The remainder of the paper is organized as follows. In
Section 1, we briefly introduce the research background as well as the aims and objectives of the proposed work. In
Section 2, the concept of IVTSFNs, their operational laws, and BMOs are briefly described. We develop the idea of the IVTSFBM, IVTSFWBM, IVTSFGBM, and IVTSFWGBM operator in
Section 3. All the listed BMOs are shown with examples. In
Section 4, we develop a method of MAGDM techniques to find the reliability and capability of the investigated operators in a practical way by using the proposed TSF BMOs. In
Section 5, we enlarge the effect of the present work by establishing a comparative study of the new work with previously defined AOs. In
Section 6, we end this paper with some concluding remarks.
2. Preliminaries
In this section, we study the idea of IVTSFNs and recall their operational laws. Here, we also elaborate on the idea of IVBMO.
Definition 1 ([
24])
. For any set , IVTSFS is of the form where and express the DM, DA, and DNM with . The DR is expressed as We define the triplet as an IVTSF number (IVTSFN). Definition 2 ([
24])
. For IVTSFNs , then Definition 3 ([
24])
. For IVTSFN , a score function is defined by:where .
Definition 4 ([
51])
. For any positive numbers with , the BMO is demonstrated by: Definition 5 ([
49])
. For any positive numbers with , the GBM operators is demonstrated by: 3. Bonferroni Mean Operators for IVTSFSs
Certain individuals have utilized the theory of BMO in the fields of IFS, PyFS, qROFS, and PFS., but no one has utilized it in the field of IVTSFS. The major contribution of this study is to combine the technique of BMO and IVTSFS to initiate the principle of the IVTSFBM operator, IVTSFWBM operator, IVTSFGBM operator, and IVTSFWGBM operator. By using the explored operators, many specific cases and important results are developed.
Definition 6 ([
24])
. For any set ,
an IVTSFN is in the form of , with . The IVTSFBM operator is a map and defined as: By using Definition 6 and Definition 2, we obtained the following result.
Theorem 1. For any set , an IVTSFN is in the form ofwithand we have: Proof. By using Equation (6), we have
By using Equation (4), we derive:
By using Equation (5), we have:
Furthermore, idempotency, monotonicity, and boundedness are desirable properties of the IVTSFBM. □
Theorem 2. For any set X, let be a collection of IVTSFNs. If allare equal, that is,then. Then, Proof . Let .
We firstly prove that
. Since
and
, we have
That is, .
Thus, we have , that is, . □
Theorem 3. For any set X, let
and
such that . Then, with , we have Proof. Let
and
. Then, by using the DM, we can prove that
. Since
and
, we have
. Moreover, we have
and
That is, . Similarly, we can show for the duplet, such that .
From the above analysis, we derive
.
□
Theorem 4. For any set , let
be a collection of IVTSFNs and bothanddenote the greatest and smallest IVTSFNs ofaccording to Definition 2. Then, Proof. Based on Equation (13), we derive , and by using Theorem 2, we , . Thus, we obtain . □
Here, it is important to note that by having the properties of boundedness and monotonicity, the
IVTSFBM operator can be used in the study of group consensus systems [
57].
By using Equation (10), we will demonstrate some cases, which is discussed below.
For
, we obtain
For
, we obtain
For
, we obtain the Intuitionistic fuzzy BMO.
For
, we obtain the Pythagorean fuzzy BMO.
Definition 7 ([
5])
. Let be a family of IVTSFNs with and , if Here, the weight vector is denoted by with a rule, that is, the sum of all is equal to 1. From Definition 7, we obtain the following result.
Theorem 5. Let be a family of IVTSFNs with. By using Equation (21) and Definition 2, we obtain Proof . The proof is similar to Theorem 1 and omitted here. □
Remark 1. The above stated theorem is likely to satisfy the properties discussed in Theorems 2–4.
Now, we discuss the geometric BM operators for IVTSFNs, which can also be regarded as duals of BM operators.
Definition 8. Letbe a family of IVTSFNs withand, if From Definition 8 and operational laws of Definition 2, we derive the following result.
Theorem 6. Letbe a family of IVTSFNs with. By using Equation (22) and Definition 2, we obtain: Proof. Straightforward. □
Furthermore, idempotency, monotonicity, and boundedness are desirable properties of the IVTSFBM as discussed in Corollaries 1–3.
Corollary 1. For any set , letbe a collection of IVTSFNs. If allare equal, that is,with, then Proof. Straightforward. □
Corollary 2. For any set , letand such that
. Then, with , we have Proof. Straightforward. □
Corollary 3. For any set ,
letbe a collection of IVTSFNs and bothanddenote the greatest and smallest IVTSFNs ofaccording to Definition 2. Then, Proof. Straightforward. □
To incorporate the weights of experts, the notion of weighted BM operators is discussed as follows:
Definition 9 ([
5])
. Let be a family of IVTSFNs with . Then, is a map defined as:
where
is a weight vector with a rule, that is, the sum of all
is equal to 1. By using Definition 9, we obtain the following result.
Theorem 7. Let be a family of IVTSFNs with. By using Equation (27), we obtain: Proof. Straightforward. □
Furthermore, idempotency, monotonicity, and boundedness are desirable properties of the IVTSFWGBM as discussed in Corollaries 1–3.
4. MAGDM Methods by Using Investigated Operators Based on IVTSFSs
In this paper, we develop a procedure of the MAGDM technique through the IVTSFBMO operator, IVTSFWBM operator, IVTSFGBM operator, and IVTSFDWGBM operator to discover the consistency and ability of the analyzed operators. Thus, select the family of alternatives with their attributes according to their weight vectors with expressions such that , where is a weight vector with a rule, that is, the sum of all is equal to 1. To cope with the above problems, take the decision matrix , whose every term is in the form of IVTSFNs, such that ; then, the procedure of the MAGDM is summarized as follow:
Step 1: Develop the decision matrices.
Step 2: Normalize the decision matrix, whose every term is in the form of IVTSFNs.
Step 3: By using the idea of the IVTSFWBM operator, aggregate the normalized decision matrices.
Step 4: Revise Step 2 again by using the idea of IVTSFWGBM operators to aggregate the decision matrices.
Step 5: Using the concept score functions, examine the score values of the aggregated values of Step 3.
Step 6: By using the score values, we rank the alternatives and examine the best one.
Step 7: The end.
Example 1. Solar panels are renewable, CO2 free, and have a low operating cost. Solar panels play an important role in the production of electricity by transforming energy from the sun to electricity. The process in which electricity is produced from the sun does not require any cost. There are many kinds of solar cells but certain kinds are discussed in our research paper. Some solar cells are organic semiconductors, such as organic solar cells, which are sometimes denoted as plastic solar cells or polymer solar cells, which are made of carbon-based material. Conversely, some solar cells are inorganic semiconductors, such as silicon solar cells, Perovskite solar cells, Hetro-junction solar cells, and triple-junction amorphous silicon alloy solar cells. Ismail Industries Limited is the largest company which is located in Faisalabad, Pakistan. Manufacturing biscuits, snacks, etc., are under the brand of candy and bissconi. Considering the limited electricity and that the industry is not able to satisfy the required task, the industry needs to produce electricity through solar energy; in such a case, the company must choose the best solar cell, which increases the generation of efficiency, lessens the cost, and is more reliable. The industry has a team of three experts who characterized the following set of alternatives to be analyzed:
: organic solar cell;
: silicon solar cell;
: Perovskite solar cell;
: triple-junction amorphous silicon alloy solar cell; and
: hetro-junction solar cell.
To judge these, the association thinks regarding the practical issue as the basis for the following year. Based on these, they need to judge procedure under the associated four commonassets:
cost of the solar cell per square meter;
power conversion efficiency;
led-free (environmentally free); and
life span of an individual solar cell.
The phases of the examined algorithm are deliberated in the following ways by using the values of weight vectors, such that. Then, execute the following steps.
Step 2: Normalize the decision matrix whose every term is in the form of IVTSFNs. All the restrained principles are of the identical type, thus they do not require the consistency done.
Step 3: Using the idea of IVTSFBO to aggregate the normalized decision matrix is discussed in the form of
Table 4.
Step 4: Revising Step 2 again by using the idea of IVTSFBM, IVTSFWBM, IVTSFGBM, and IVTSFWGBMO to aggregate the decision matrix is discussed in the form of
Table 5.
Step 5: Both the using of the concept score functions and the examining of the score values of the aggregated values of Step 3 are discussed in the form of
Table 6.
The graphical expressions of the information in
Table 6 are discussed in the form of
Figure 1.
By using the information in
Table 5, the geometrical expression is discussed in the form of
Figure 1.
Step 6: By using the score values, we rank the all-score values and examine the best one in the form of
Table 7.
As shown above, the best optimal is by using the IVTSFWBMO and it is by using IVTSFWGBMO. Note that the choice of the operator is up to the decision maker and the results using both BM operators may vary. Furthermore, these results are more reliable in comparison to the results obtained using traditional AOs because of the property of the connection of input arguments using the BM operators. Further details about the reliability of the proposed approach is discussed in the next section.