Reino Kurki-Suonio has a PhD in mathematics from the University of Helsinki. He entered the field of computing in 1960. In 1965 he moved from industry to the University of Tampere to start the first computer science department in Finland. In 1980 he was invited to develop education in information technology at Tampere University of Technology, where he currently serves as professor emeritus at the Institute of Software Systems. During his career he has held visiting positions at Carnegie Mellon and Stanford Universities, and has served as the Chair of IFIP Technical Committee on Software, Theory and Practice.

Prologue.- Components of a Theory.- Fundamentals.- Towards an Action Language.- Formal Properties of Behaviors.- Proving Behavioral Properties.- Building a Practical Theory.- Basic Language Facilities.- Fundamentals of Design Methodology.- Object Orientation Elaborated.- Components and Interfaces.- Distributed and Real-Time Systems.- Distributed Systems.- Real Time.- Epilogue.- Reexamining the Theory.

A man may imagine he understands something, but still not understand anything in the way that he ought to. (Paul of Tarsus, 1 Corinthians 8:2) Calling this a 'practical theory' may require some explanation. Theory and practice are often thought of as two di?erent worlds, governed bydi?erentideals,principles, andlaws.DavidLorgeParnas, forinstance,who hascontributedmuchtoourtheoreticalunderstandingofsoftwareengineering and also to sound use of theory in the practice of it, likes to point out that 'theoretically' is synonymous to 'not really'. In applied mathematics the goal is to discover useful connections between these two worlds. My thesis is that in software engineering this two-world view is inadequate, and a more intimate interplay is required between theory and practice. That is, both theoretical and practical components should be integrated into a practical theory. It should beclearfrom theabovethattheintended readership of this book is not theoreticians. They would probably have di?culties in appreciating a book on theory where the presentation does not proceed in a logical sequence from basic de?nitions to theorems and mathematical proofs, followed by - plication examples. In fact, all this would not constitute what I understand by a practical theory in this context.