"Concurrency and Nets" is a special volume in the series "Advances in Petri Nets." Prepared as a tribute to Carl Adam Petri on the occasion of his 60th birthday, it is devoted to an outstanding personality and his pioneering and fruitful scientific work. Part I (70 pages of over 600) presents the congratulatory addresses and invited talks that were given at an Anniversary Colloquium. The contributions of this part honor Carl Adam Petri and his work from many different perspectives. Part II is a collection of invited papers discussing various aspects of the theme Concurrency and Nets. These papers are contributed partly by researchers that were or are still associated with the Petri Institute at GMD and partly by researchers whose scientific work deals with Net Theory or related system models. The topics range from basic theoretical aspects to application oriented methods.

Man wird dem einzelnen nicht gerecht, wenn man es gesondert ins Auge jaftt, ohne seinen Zusammenhang mit dem Ganzen zu beachten und dem Beziehungssystem Rechnung zu tragen, in dem es steht. Thomas Mann Science in general, as well as in each of its individual fields, is a part of human culture. In that sense, this book aims to contribute to uncovering a small part of the connections and relationships which bind image processing, categorized in informatics and technology, with the knowledge accumulated over the years on discrete structures. How does one consider problems, models, mathematical methods and prac- tical applications? How does the search for ideas and the endeavour for know- ledge in the original work of scientists find expression? Is there something to be learnt from science to date for future developments? Such questions have shaped the content and style of this book. Substantial impetus to the discrete theory of image processing was afforded by the work of Rosenfeld and colleagues. Other fruitful sources of ideas con- sidered here are number theoretical problems (GauB, Minkowski) and integral geometric investigations (Blaschke, Santalo). Since the beginning of the 1980s I have strived to build upon these ideas a unified mathematical representation of discrete image processing working together with R.K1ette and P.Hufnagl.