This volume documents the progress of application and theory of Petri Nets since the Advanced Course on General Net Theory of Processes and Systems, held in Hamburg, October 8-19, 1979, This course presen ted in detail wha t had been achieved in this area since the first studies of concurrent systems 20 years ago, After this course it seemed worthwhile to establish a co-operation between different groups working in the field of Petri N ets, The starting points were the AFCET Special Interest Group "Systemes Paralleles et Distribues" and the Gl Special Interest Group "Petrinetze und verwandte Systemmodelle", Meanwhile, group s of many European countries are involved, A main activity of this co-operation is the realization of workshops in varying European countries, The first workshop of this kind was carried out in Strasbourg (France), September 23-26, 1980, The second one took place in Bad Honnef (Germany) September 28-30, 1981. This volume contains contributions of these two workshops, The 1980 workshop in Strasbourg was partitioned into 6 topics : (1) Application of Nets to Realtime Systems, (2) Programming Languages and Software Engineering, (3) Information Flow and Concurrency, (4) Net Morphisms and High Level Petri Nets, (5) Mathematical Analysis and N et Languages, (6) Reliability and Recovery Issues, In this volume, the chairman of each topic gives a short introduction to his area whict should help to understand its specific problems and to in troduce the presented papers,weiterlesen