Abstract
Recently, the TODIM has been used to deal with multiple attribute decision making (MADM) problems. The intuitionistic 2-tuple linguistic sets (I2TLSs) are useful tools to depict uncertainty in MADM. This paper use TODIM method to solve MADM with the intuitionistic 2-tuple linguistic numbers (I2TLNs). Firstly, the concepts of I2TLNs are briefly presented, and classical TODIM for MADM are introduced. Then, the classical TODIM method is used to solve MADM with I2TLNs, and its important characteristic is to fully consider the decision makers’ bounded rationality which is a real action in MADM. And a comparative analysis is also given. Finally, a numerical example for service outsourcing providers selection is proposed.
Keywords

Introduction
Zadeh [1] designed the fuzzy set (FS) and opened the door to a new field of fuzzy theory in 1965. As a very useful and effective tool, it is applicable to various fields [2]. It could be founded the footprint and research results from the engineering science and technology to the social and human sciences [3, 4, 5]. To extend Zadeh’s classical fuzzy set, the intuitionistic fuzzy set (IFS), which takes into account the membership degree, the non-membership degree and the hesitancy degree [6] at the same time, was developed and studied by Atanassov [7, 8] in 1986 and 1989. Bao et al. [9] defined an intuitionistic fuzzy decision method based on prospect theory and the evidential reasoning approach which aiming at analyzing MADM problems in which the criteria values are intuitionistic fuzzy numbers and the information of attributes weights is unknown. Chen and Wang [10] investigated the MADM problems for evaluating the performance of projects loaned by international financial organizations with the fuzzy number intuitionistic fuzzy numbers (FNIFNs). Damgaci et al. [11] defined the evaluation of appropriate renewable energy sources for Turkey considering technical, economic, environmental and social factors by using Intuitionistic Fuzzy TOPSIS Method. Das et a. [12] investigated the EBM operator with Atanassov’s intuitionistic fuzzy sets (AIFSs) by using additive generators of strict t-conorms in the operations of AIFSs. Liang et al. [13] discussed the decision principles of three-way decision rules based on the variation of loss functions with intuitionistic fuzzy sets (IFSs) and introduced the intuitionistic fuzzy point operator (IFPO) into DTRSs and explore three-way decisions. Liu et al. [14] proposed two prioritized aggregation (PA) operators for HIFLSs: prioritized weighted averaging operator for HIFLSs (HIFLPWA) and prioritized weighted geometric operator for HIFLSs (HIFLPWG). Liu et al. [15] proposed a novel approach for multi-attribute group decision making problem (MAGDM) with trapezoidal intuitionistic fuzzy numbers (TIFNs). Jiang et al. [16] proposed a new type of operator called an intuitionistic fuzzy entropy weighted power average aggregation operators. Li et al. [17] used dynamic intuitionistic fuzzy weighted geometric (DIFWG) operator to integrate different time periods of the intuitionistic fuzzy decision matrices. Xu [18] investigated the MADM problems, in which attribute weights is incomplete and the attribute values are depicted in intuitionistic fuzzy numbers (IFNs). Chen [19] proposed a useful model of relating optimism and pessimism to MCDM in the context of IFSs based on the unipolar bivariate model. Wan and Li [20] built a new intuitionistic fuzzy programming model to solve heterogeneous multi-attribute GDM problems with intuitionistic fuzzy truth degrees in which there are four types of attribute values such as IFSs, trapezoidal fuzzy numbers, intervals, and real numbers. Lu and Wei [21] designed the TODIM method for performance appraisal on social-integration-based rural reconstruction under IVIFSs. Wu et al. [22] proposed some interval-valued intuitionistic fuzzy Dombi Heronian mean operators for evaluating the ecological value of forest ecological tourism demonstration areas. Wu et al. [23] designed the algorithms for competiveness evaluation of tourist destination with some interval-valued intuitionistic fuzzy Hamy mean operators. Wu et al. [24] gave the VIKOR method for financing risk assessment of rural tourism projects under IVIFSs.
Although, intuitionistic fuzzy set (IFS) theory has been successfully applied in some areas, the IFS is also characterized by the membership degree and the non-membership degree, whose sum is less than or equal to 1. However, all the above approaches are unsuitable to describe the membership degree and the non-membership degree of an element to a set by linguistic variables on the basis of the given linguistic term sets, which can reflect the decision maker’s confidence level when they are making an evaluation. In order to overcome this limit, Wei [25] proposed the concept of 2-tuple intuitionistic linguistic sets (2TILSs) to solve this problem based on the IFSs and 2-tuple linguistic information processing model [26, 27, 28]. Beg and Rashid [29] defined the intuitionistic 2-tuple linguistic sets (I2LSs). Until now, there is no scholar to investigate the TODIM model under intuitionistic 2-tuple linguistic sets (I2TLSs). Thus, it is very necessary to keep a watchful eye on this novel and worthy issue. The purpose of our paper is to use the TODIM idea to cope with the MADM with the I2TLSs, to fill up this vacancy. For Section 2, we introduce the definition of IFSs and I2TLSs and classical TODIM method for MADM problems. We develop the TODIM model to solve the MADM under I2TLSs in Section 3. An illustrative example for service outsourcing providers selection is pointed out and a comparative analysis is given in Section 4. We give a conclusion in the Section 5.
Preliminaries
In the following, some basic concepts related to I2TLSs and IFSs are introduced.
2-tuple linguistic term sets
Let
(1) The set is ordered:
Herrera and Martinez [26] defined the 2-tuple fuzzy linguistic information model based on the definition of symbolic translation. It is employed for depicting the linguistic information by means of a 2-tuple
where round(.) is the usual round operation,
From Definitions 1 and 2, we can conclude that the conversion of a linguistic term into a linguistic 2-tuple consists of giving a value 0 as symbolic translation:
Atanassov [7] extended the fuzzy set to the IFS, defined as follows:
Where
to evaluate the degree of accuracy of
In the following, Beg and Rashid [29] defined the concepts of the intuitionistic 2-tuple linguistic sets (I2TLSs) on the basis of the IFSs and 2-tuple linguistic information model.
where
The TODIM approach [32], developed to consider the DM’s psychological behavior, can effectively solve the MADM problems. Based on the prospect theory, this approach depicts the dominance of each alternative over others by constructing a function of multi-attribute values [33, 34].
Let
where
and the parameter
The following mathematical notations are used to depict the MADM problems with I2TLNs. Let
To solve the MADM problem with I2TLNs, we shall define the intuitionistic 2-tuple linguistic TODIM (I2TL-TODIM) method, which is proposed based on the prospect theory and can depict the DMs’ behaviors under risk.
Firstly, we calculate the relative weight of each attribute
where
Based on the Eq. (15), we can derive the dominance degree of
where the parameter
In order to indicate the functions
based on which we could derive the overall dominance degree of the
Therefore, by Eq. (18), the overall dominance degree matrix can be got as:
Finally, the overall value of each
And the order of each alternative can be ranked by the principle, that is, the greater the overall value
Numerical example
Outsourcing has become a global business development trend, when enterprises face competitive challenges, and excellent outsourcing supply manufacturers, suppliers can use all the resources, so that enterprises can focus on their core functions and capabilities, improve production, profitability, reduce costs, increase enterprise competitive advantage. Thus, in this section we shall present a numerical example for selecting the service outsourcing provider with I2TLNs in order to illustrate the method proposed in this paper. Let us suppose there is a problem for selecting the service outsourcing provider which is classical MADM problems. There is a panel with five possible service outsourcing providers of communications industry
The decision matrix with I2TLNs
The decision matrix with I2TLNs
Then, we use the proposed I2TL-TODIM method to select the best service outsourcing providers of communications industry.
Firstly, since
Secondly, the overall dominance degree of the candidate
Then, we derive the overall value
Finally, we determine the ranking of the alternatives according to the overall values
The MADM methods are widely applied in real-life decision-making situations, and the TODIM method which could fully consider DM’s bounded rationality. Additionally, the intuitionistic 2-tuple linguistic sets (I2TLSs) are more easily express uncertain or fuzzy information. Therefore, it is meaningful and valuable to research uncertain MADM problems with the I2TLNs which considering the behavior preferences of the DMs. This paper use TODIM method to solve MADM with the I2TLNs. Firstly, the definition, comparison and distance of I2TLNs are briefly introduced, and classical TODIM for MADM are introduced. Then, the intuitionistic 2-tuple linguistic TODIM (I2TL-TODIM) method is defined to deal with MADM problems, and its important characteristic is to fully consider the decision makers’ bounded rationality which is a real action in practical MADM. Finally, a numerical example for service outsourcing providers selection is proposed and a comparative analysis is also given. In our future researches, the proposed models and methods of I2TLNs needs to be extended in the MADM [35, 36, 37, 38, 39, 40], risk assessment [41, 42, 43] and some other uncertainty and fuzziness [44, 45, 46, 47, 48].
Footnotes
Acknowledgments
The work was supported by the Humanities and Social Sciences Foundation of Ministry of Education of the People’s Republic of China (No. 14YJA630017).
