Operations Research is the discipline of applying advance analytical methods to help make better decisions. It helps the management to achieve its goals by using scientific techniques, making the study and understanding of operations research even more important in the present –day scenario. This book has been written with the objective of providing students with a comprehensive textbook on the subject. It follows a simple algorithmic approach to explain each concept, often giving different steps. This approach stems from the author’s experience in teaching undergraduate and postgraduate students over many years. The intended readers of this book are senior undergraduate students, graduate students, researchers and practitioner in the fields of operations research, mathematics, industrial engineering, management science, and other engineering disciplines that deal with the subjects of hierarchical decision making problems.