"Three years ago, when the second edition of this text was published, we mentioned our goal of building on the positive elements of the first edition and including what we had learned subsequently. We are pleased to note that that revision was successful; as with the first edition, we received a tremendous response from adopters, students, executives, and consultants. Nevertheless, new concepts have subsequently been developed, technological changes continue at an ever-increasing rate, and we have discovered a variety of important new teaching approaches and concepts, so the time is right for a newly revised edition. The original edition of this book grew out of a number of supply chain management courses and executive education programs we taught at Northwestern University, as well as numerous consulting projects and supply chain decision-support systems we developed at LogicTools. Since then, we have continued teaching executive and regular courses, both at Massachusetts Institute of Technology and at the University of California, Berkeley, and have continued to develop a variety of supply chain decisionsupport tools. These courses have spawned many innovative and effective supply chain education concepts. The focus in these programs has always been on presenting, in an easily accessible manner, recently developed state-of-the-art models and solution methods important in the design, control, and operation of supply chains. Similarly, the consulting projects and decision-support systems developed by LogicTools have focused on applying these advanced techniques to solve specific problems faced by our clients.

In the last three years, we have continued to add new models and techniques to these courses as they have been developed, and we continued the process of integrating these approaches, models, and solution methods into frameworks so that students can better put these ideas into perspective. Interest in supply chain management, both in industry and in academia, has grown rapidly over the past two decades, and continues to grow. A number of forces have contributed to this trend. In the 90s, many companies recognized that they have reduced manufacturing costs as much as practically possible. Many of these companies discovered the magnitude of savings that can be achieved by planning and managing their supply chains more effectively. Indeed, a striking example in the 90s was Wal-Mart's success, which is partly attributed to implementing a new logistics strategy called cross-docking. At the same time, information and communication systems were widely implemented, and provide access to comprehensive data from all components of the supply chain. In particular, the influence of the Internet and e-commerce on the economy in general and business practice in particular has been tremendous.

Changes are happening extremely fast, and the scope of these changes is breathtaking! For instance, the direct business model employed by industry giants such as Dell Computers and Amazon.com enables customers to order products over the Internet and thus allows companies to sell their products without relying on third-party distributors or conventional stores. Similarly, the Internet has made a significant impact on business-tobusiness transactions and collaborations. At the same time, deregulation of the transportation industry has led to the development of a variety of transportation modes and reduced transportation costs, while significantly increasing the complexity of logistics systems"--.