Sezi Cevik Onar

Multi-criteria decision-making (MCDM) methods often involve uncertainty and subjective judgment. The Analytic Hierarchy Process (AHP) has been widely used to structure and solve such problems, and its extension with intuitionistic fuzzy sets (IF-AHP) allows for modeling both membership and non-membership degrees. However, ordinary intuitionistic fuzzy sets may not fully capture complex uncertainties that include phase or directional information. This paper proposes a Complex Intuitionistic Fuzzy AHP (CIF-AHP) approach, integrating complex intuitionistic fuzzy sets into the traditional AHP framework. The methodology is applied to capture consumers’ purchasing preferences regarding electric vehicles (EVs) under uncertainty, and a comparative analysis is conducted between CIF-AHP and ordinary IF-AHP. The results demonstrate that CIF-AHP provides richer information and enhanced differentiation among alternatives, offering a more nuanced decision-making tool in uncertain environments. The contribution of this study to the literature lies in identifying and weighting the key factors influencing EV adoption through a method that explicitly accounts for vagueness and hesitation in decision-making.

Sustainable material selection has become a crucial challenge in the construction industry due to increasing environmental concerns, resource limitations, and the demand for long-term ecological balance. Traditional evaluation approaches often struggle to adequately address the complexity and uncertainty inherent in expert judgments. To overcome these limitations, this study proposes a novel decision-making framework based on the Complex Intuitionistic Type-2 Fuzzy Analytic Hierarchy Process (CIT2F-AHP). The method integrates the strengths of fuzzy set theory and analytic hierarchy process to capture both magnitude and phase information, enabling a more robust representation of expert opinions under uncertainty. A comprehensive set of evaluation criteria covering environmental, technical, economic, social, and regulatory aspects is adopted for assessing sustainable alternatives. The proposed approach is applied to compare low-carbon cement and concrete options, including carbon-cured concrete, geopolymer concrete, alkali-activated binders, and limestone calcined clay cement. The findings highlight the effectiveness of CIT2F-AHP in ranking sustainable materials and demonstrate its potential as a reliable decision-support tool for practitioners and policymakers in advancing green construction practices.