Preface

This volume contains the proceedings of SOS 2011, the Eight Workshop on Structural Operational Semantics, held on the 5th of September 2011 in Aachen, Germany as an affiliated workshop of CONCUR 2011, the 22nd International Conference on Concurrency Theory.

Structural operational semantics (SOS) provides a framework for giving operational semantics to programming and specification languages. A growing number of programming languages from commercial and academic spheres have been given usable semantic descriptions by means of structural operational semantics. Because of its intuitive appeal and flexibility, structural operational semantics has found considerable application in the study of the semantics of concurrent processes. It is also a viable alternative to denotational semantics in the static analysis of programs, and in proving compiler correctness. Moreover, it has found application in emerging areas of computing such as probabilistic systems and systems biology.

Structural operational semantics has been successfully applied as a formal tool to establish results that hold for classes of process description languages. This has allowed for the generalization of well-known results in the field of process algebra, and for the development of a meta-theory for process calculi based on the realization that many of the results in this field only depend upon general semantic properties of language constructs.

The workshop is a forum for researchers, students and practitioners interested in new developments and directions for future investigations. One of the specific goals of the workshop is to provide a meeting point for the concurrency and programming language communities. Another goal is the dissemination of the theory and practice of SOS amongst postgraduate students and young researchers worldwide.

SOS'11 featured an invited lecture by Wan Fokkink (jointly with EXPRESS'11).

The submitted papers were carefully refereed by the programme committee:

• Luca Aceto (Reykjavik, IS)
• Simon Bliudze (CEA-LIST, FR)
• Filippo Bonchi (Ecole Normale Superieure, FR)
• Fabio Gadducci (Pisa, IT)
• Matthew Hennessy (Dublin, IR)
• Bartek Klin (Warsaw, PL)
• Keiko Nakata (Tallinn, EST)
• Michel Reniers (Eindhoven, NL, co-chair)
• Pawel Sobocinski (Southampton, UK, co-chair)
• Sam Staton (Cambridge, UK)
• Daniele Varacca (Paris VII, IT)

Why Modal Characterizations of Process Semantics Totally Rock

I will give a survey of recent results on the relation between structural operational semantics, modal logic, and process algebra. The following three topics will be discussed.

1. Given a modal characterization of a semantics, one can derive a congruence format for this semantics in the context of structural operational semantics.
2. Given transition rules for a process operator, one can derive requirements on modal characterizations to guarantee that the corresponding semantics is a congruence for this operator.
3. Necessary and sufficient requirements have been given on modal characterizations to guarantee that the corresponding semantics is sound for the proof principle AIP.