Preface: Special Issue on Modeling, Simulation, and Optimization in Operational Research

By using techniques such as problem structuring methods and mathematical modeling to analyze nontrivial situations, OR gives executives the power to make more effective decisions and build more productive systems. In all of these items, modern Optimization and Optimal Control, Data Mining, Machine Learning, OR and AI come into action and service as key technologies of model selection, modeling, regularization and of careful pre- and post-processing, of design and preparation, of guidance and interest, of continuous concern, trust and responsibility. In the third paper, Subrata Panja and Shyamal Kumar Mondal presented “Analytics of an Imperfect Four-Layer Production Inventory Model Under Two-Level Credit Period Using Branch-and-Bound Technique”. In the fifth paper, Zahra Behdani and Majid Darehmiraki introduced “An Alternative Approach to Rank Efficient DMUs (decision-making units) in DEA (data envelopment analysis) via Cross-Efficiency Evaluation, Gini Coefficient and Bonferroni Mean”.