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    A Comparative Analysis of the Ranking Functions for the IVIFVs and A New Score Function
    (Gazi Univ, 2022) Kokoc, Melda; Ersoz, Suleyman
    The ranking of interval-valued intuitionistic fuzzy values (IVIFVs) has an important role in real-life decision-making problems. Even though there are many approaches related to the ranking methods of the IVIFVs, some of them have some shortcomings. In this study, the disadvantages of the existing ranking functions of the IVIFVs are discussed. It is revealed that both the most popular ranking functions and their recently improved versions may lead to unacceptable results. Furthermore, in this article, a new score function is offered to cope with the shortcomings of the ranking functions. The importance and performance of this new score function are proven with the help of many examples. Also, the decision-making algorithm adapted by integrating the new function is presented to illustrate the applicability of the new score function in the decision-making problems.
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    A comparison of the performance of entropy measures for interval- valued intuitionistic fuzzy sets
    (Yildiz Technical Univ, 2021) Kokoc, Melda; Ersoz, Suleyman
    Entropy measure is a significant tool to define unclear information. But, entropy measures for interval-valued intuitionistic fuzzy sets (IVIFSs) cannot be easily understood intuitively. So, it is highly important to compare the existing measures to select a reliable entropy measure in studies. The purpose of this study is to compare the performance of different entropy measures developed for IVIFSs. The numerical examples are presented to show whether entropy measures for IVIFSs are effective in representing the fuzziness degree. In order to understand whether a variation of fuzziness degree of one or more elements of IVIFSs change the ranking results, selected IVIFSs are modified diversely.
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    A LITERATURE REVIEW OF INTERVAL-VALUED INTUITIONISTIC FUZZY MULTI-CRITERIA DECISION-MAKING METHODOLOGIES
    (Wroclaw Univ Science & Technology, Fac Management, 2021) Kokoc, Melda; Ersoz, Suleyman
    Multi-criteria decision-making (MCDM) is one of the most popular problems handled by researchers in the literature. Since the interval-valued intuitionistic fuzzy set (IVIFS) theory generates as realistic as possible evaluation of linguistic expressions, researchers have been expanding traditional MCDM methods to the IVIF environment, especially in the last decade. This study provides a literature review of the relevant articles from several academic databases on applications of IVIF-MCDM methods. The review of 131 publications addresses specific research questions. To understand the research publication trend, this review offers a visual analysis that examines the studies from different perspectives, such as application areas, IVIF-MCDM methods, citations, most relevant journals, and validation methods. One of the most remarkable results of the literature review is that most publications in this field are published in SCIE indexed journals. Another noteworthy issue is that China is the country that produces the most articles in this field. In addition, English journals are mostly selected for the publication of articles. While it is seen that the investment selection problem is chosen mostly as the application area, the TOPSIS method is preferred mostly in the applications. This study stands out as the most comprehensive one that compiles publications containing extended traditional MCDM methods for IVIF sets. This review will be an important reference for future researchers and decision-makers involved in advancing MCDM methods considering vagueness and ambiguity.
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    Creating Alternative Layout Plans with Simulated Annealing and Data Mining
    (Ieee, 2017) Kokoc, Melda; Aktepe, Adnan; Ersoz, Suleyman
    When studies in literature are examined, it is seen that different approaches have been used to solve facility layout problems. The relationship between departments in layout is always important. In this study, data mining technique is used for analyzing relations among departments and then association rules are obtained. Determining closeness relationships between the departments in facility are often ambiguous and require expert opinions. In such cases, a fuzzy component emerges in the facility layout problem. Hence, fuzzy logic is widely used to address ambiguous problems. Association rules is converted by using defuzzification approach to crisp values used facility layout problem solution in this study. Facility layout problems are considered to be NP-Hard (Nondeterministic-Polynomial-Hard) optimization problems. That is, definite solution approaches are limited in solving large-scale problem examples. For heuristic approaches are frequently used to improve the layout, simulated annealing approach is used in this study. To improve facility layout planning, simulated annealing approach is carried out via code written in Visual Basic 2012. In conclusion, 17% improvement is achieved with alternative layout plan obtained.
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    New Ranking Functions for Interval-Valued Intuitionistic Fuzzy Sets and Their Application to Multi-Criteria Decision-Making Problem
    (Inst Information & Communication Technologies-Bulgarian Acad Sciences, 2021) Kokoc, Melda; Ersoz, Suleyman
    Many authors agree that the Interval-Valued Intuitionistic Fuzzy Set (IVIFS) theory generates as realistic as possible evaluation of real-life problems. One of the real-life problems where IVIFSs are often preferred is the Multi-Criteria Decision Making(MCDM) problem. For this problem, the ranking of values obtained by fuzzing the opinions corresponding to alternatives is an important step, as a failure in ranking may lead to the selection of the wrong alternative. Therefore, the method used for ranking must have high performance. In this article, a new score function S-KE and a new accuracy function H-KE are developed to overcome the disadvantages of existing ranking functions for IVIFSs. Then, two illustrative examples of MCDM problems are presented to show the application of the proposed functions and to evaluate their effectiveness. Results show that the functions proposed have high performance and they are the eligibility for the MCDM problem.
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    New Score and Accuracy Function for IVIF Sets and Their Applications to AHP for MCGDM
    (Taylor & Francis Inc, 2022) Kokoc, Melda; Ersoz, Suleyman
    Multi-criteria group decision making (MCGDM) is an important part of decision science and widely applied in several fields. To cope with the vagueness and ambiguity of the human evaluation in the MCGDM process, interval-valued intuitionistic fuzzy set (IVIFS) theory is introduced. In this study, the AHP method whose traditional form is frequently used in MCGDM problems is improved in the IVIF environment. Since the aim of AHP is to choose the most suitable criterion/alternative by making a rank from the most important to the least important, the improved IVIF-AHP method is based on the ranking functions. Some existing score and accuracy functions are analyzed and it is seen that these functions have some limitations to rank IVIF numbers. So, new score and accuracy functions of IVIFS are developed to overcome their limitations and these new functions are integrated into the IVIF-AHP method. The comparative results show that the improved IVIF-AHP method gives a consistent ranking for the criteria. Moreover, the proposed method steps are illustrated with a case study about prioritizing some technical and soft skills over industrial engineering and electrical engineering.