*2.3. Ordinal Optimization Approach (OOA)*

Ho et al. [55] introduced the key cogitation of the OOA to reduce the process of searching for global optimal solutions blindly. Ordinal comparison and goal softening procedures are the major processes employed in the OOA. The approach looks for reliable and satisfactory solutions by searching through the relative rankings of each solution instead of directly evaluating the optimal solution in a complex optimization model. Thus, relatively better solutions are selected and used in the optimization process, and the best solution can be obtained without meaningless calculations and iterations of the worst solutions.
