This book is based upon work done under the project "Correct Software through Formal Methods" supported by the German Ministry of Research and Technology. As a case-study report on the practice of formal software development, this book systematically presents and compares 18 different approaches to the control of a real-world production cell. Mathematically precise, formal methods play an increasingly important role in software development, particularly in areas where failure of software would result in injury to people or, at best, significant loss of money. By analyzing the benefits and explaining the use and limitations of formal methods on a sample basis, this book provides a roadmap for the selection and application of appropriate approaches and thus helps in putting formal methods into industrial use.