The aim of software engineering is the provision and investigation of methods for the development of software systems of high quality with correctness as a key issue. A system is called correct if it does what one wants, if it meets the requirements. To achieve and to guarantee correct systems, the need of formal methods with rigorous semantics and the possibility of verification is widely accepted. Algebraic specification is a software engineering approach of this perspective. When Liskov and Zilles, Guttag and the ADJ-group with Goguen, Thatch er, Wagner and Wright introduced the basic...