G. Rozenberg – författare

This volume presents a selection of papers presented at the 3rd European Workshop on Appl ications and Theory of Petri Nets that took place in Villa Monastero, Varenna (Italy) in the period September 27 - September 30, 1982. The I ist of topics included: nets and related models, mathematical analysis of nets, transformations and morphisms of nets, formal languages and nets, parallel program verification and nets, the pro­ blem of time in nets, programming languages based on nets, applications to distributed systems, applications to realtime systems, software ~~gineering, hardware design and its implementation, recoverability problems, nets and formal semantics; net tools. The diversity of topics on this list witnesses the fact that the researchers from very different areas presented their contributions and discussed various research problems during the workshop. This interaction of scientists looking at the area of Petri nets from very different points of view makes this series of workshops interesting and worthwi le. The volume documents the progress of the research concerning Petri nets during a one­ year time from the 2nd European Workshop held in Bad Honnef in 1981. We think that this was a substantial progress indeed. This observation is even more pleasant if one real izes that during the workshop in Varenna we have celebrated 20 years of "existence" of Petri nets (the seminal work by prof. C.A. Petri appeared precisely 20 years ago). We are very proud to present an invited address by prof. C.A. Petri in this volume.

Over the last few years, object-oriented programming has been recognized as the best way currently available of structuring software systems. It emphasizes grouping together data and the operations performed on them, encapsulating the whole behind a clean interface, and organizing the resulting entities in a hierarchy based on specialization in functionality. In this way it provides excellent support for the construction of large systems. Up to now, there has been relatively little effort to develop formal theories of object-oriented programming. However, for the field to mature, a more formal understanding of the basic concepts of object-oriented programming is necessary. This volume presents the proceedings of the School/Workshop on Foundations of Object-Oriented Programming (FOOL) held in Noordwijkerhout, The Netherlands, May 28 - June 1, 1990. The workshop was an activity of the project REX (Research and Education in Concurrent Systems).

In the past decade, the formal theory of specification,verfication and development of real-time programs has grownfrom work of a few specialized groups to a real "bandwagon".Many eminent research groups have shifted their interests inthis direction. Consequently, research in real-time is nowentering established research areas in formal methods, suchas process algebra, temporal logic, and model checking.This volume contains the proceedings of a workshop dedicatedto the theory of real-time with the purpose of stepping backand viewing the results achieved as well as considering thedirections of ongoing research. The volume gives arepresentative picture of what is going on in the fieldworldwide, presented by eminent, active researchers. Thematerial in the volume was prepared by the authors after theworkshop took place and reflects the results of the workshopdiscussions.

Researchers working on the semantics of programminglanguages came together in The Netherlands in June 1992 fora workshop on Semantics - Foundations and Applications. Thisvolume is based on the meeting and contains materialprepared by the lecturers after the meeting took place. Thevolume includes papers on a wide range of topics in bothfoundationsand applications, including:- Comparative domain theory, category theory, informationsystems,- Concurrency: process algebras, asynchronous communication,action semantics, trace nets, process refinement, concurrentconstraint programming,- Predicate transformers, refinement,weakest preconditions,- Comparative semantics of programming concepts, fullabstraction,- Reasoning about programs: total correctness, epistemiclogic,- Logic programming,- Functional programming: sequentiality, integration withconcurrency, applied structured operational semantics.The workshop was an activity of the project REX (ResearchandEducation in Concurrent Systems) sponsored by theNetherlands NFI (NationaleFaciliteit Informatica)Programme.

The REX School/Symposium "A Decade of Concurrency - Reflections and Perspectives" was the final event of a ten-year period of cooperation between three Dutch research groups working on the foundations of concurrency. Ever since its inception in 1983, the goal of the project has been to contribute to the cross-fertilization between formal methods from the fields of syntax, semantics, and proof theory, aimed at an improved understanding of the nature of parallel computing. The material presented in this volume was prepared by the lecturers (and their coauthors) after the meeting took place. In total, the volume constitutes a thorough state-of-the-art report of the research activities in concurrency.

This third volume of the Handbook of Formal Languages discusses language theory beyond linear or string models: trees, graphs, grids, pictures, computer graphics. Many chapters offer an authoritative self-contained exposition of an entire area. Special emphasis is on interconnections with logic.

This volume presents a selection of papers presented at the 3rd European Workshop on Appl ications and Theory of Petri Nets that took place in Villa Monastero, Varenna (Italy) in the period September 27 - September 30, 1982. The I ist of topics included: nets and related models, mathematical analysis of nets, transformations and morphisms of nets, formal languages and nets, parallel program verification and nets, the pro­ blem of time in nets, programming languages based on nets, applications to distributed systems, applications to realtime systems, software ~~gineering, hardware design and its implementation, recoverability problems, nets and formal semantics; net tools. The diversity of topics on this list witnesses the fact that the researchers from very different areas presented their contributions and discussed various research problems during the workshop. This interaction of scientists looking at the area of Petri nets from very different points of view makes this series of workshops interesting and worthwi le. The volume documents the progress of the research concerning Petri nets during a one­ year time from the 2nd European Workshop held in Bad Honnef in 1981. We think that this was a substantial progress indeed. This observation is even more pleasant if one real izes that during the workshop in Varenna we have celebrated 20 years of "existence" of Petri nets (the seminal work by prof. C.A. Petri appeared precisely 20 years ago). We are very proud to present an invited address by prof. C.A. Petri in this volume.

This book is dedicated to Aristid Lindenmayer on the occasion of his 60th birthday on November 17, 1985. Contributions range from mathematics and theoretical computer science to biology. Aristid Lindenmayer introduced language-theoretic models for developmental biology in 1968. Since then the models have been cus­ tomarily referred to as L systems. Lindenmayer''s invention turned out to be one of the most beautiful examples of interdisciplinary science: work in one area (developmental biology) induces most fruitful ideas in other areas (theory of formal languages and automata, and formal power series). As evident from the articles and references in this book, the in­ terest in L systems is continuously growing. For newcomers the first contact with L systems usually happens via the most basic class of L systems, namely, DOL systems. Here "0" stands for zero context between developing cells. It has been a major typographical problem that printers are unable to distinguish between 0 (zero) and 0 (oh). Thus, DOL was almost always printed with "oh" rather than "zero", and also pronounced that way. However, this misunderstanding turned out to be very fortunate. The wrong spelling "DOL" of "DOL" could be read in the suggestive way: DO L Indeed, hundreds of researchers have followed this suggestion. Some of them appear as contributors to this book. Of the many who could not contribute, we in particular regret the absence of A. Ehrenfeucht, G. Herman and H.A. Maurer whose influence in the theory of L systems has been most significant.