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,