Robust Fully Fuzzy Programming with Fuzzy Set Ranking Method for Environmental Systems Planning Under Uncertainty

This article proposes a new robust interactive interval fully fuzzy linear programming (RIIFFLP) method, using the fuzzy ranking method to find a balance between the requirements of constraints and the objective function of a fuzzy set function, as a technique for optimal decision-making under uncertainty. It considerably improved previous interval fuzzy linear programming (FLP) methods by using a new solution method named the robust two-step method (RTSM). The RTSM has a higher membership degree for the fuzzy subset, which allows interval results to stay within the boundaries of constraints. This RIIFFLP model was applied to a case study in municipal solid waste management. Results demonstrated that the solution obtained from the RIIFFLP model had more feasible results by comparison with existing FLP methods. The RIIFFLP also provided optimal interval solutions in different α levels that made decision making easier by simply choosing a suitable scenario. Therefore, the RIIFFLP model can be considered a better practical method for problem-solving when uncertainties are present.