Published: 24th August 2018
DOI: 10.4204/EPTCS.276
ISSN: 2075-2180


Proceedings Combined 25th International Workshop on
Expressiveness in Concurrency
and 15th Workshop on
Structural Operational Semantics
Beijing, China, September 3, 2018

Edited by: Jorge A. Pérez and Simone Tini

Invited Presentation: On Milner's Axiomatization for Regular Expressions
Wan Fokkink
Invited Presentation: Adventures in Monitorability
Adrian Francalanza
Context-Free Session Types for Applied Pi-Calculus
Jens Aagaard, Hans Hüttel, Mathias Jakobsen and Mikkel Kettunen
Trace and Testing Metrics on Nondeterministic Probabilistic Processes
Valentina Castiglioni
A Classification of BPMN Collaborations based on Safeness and Soundness Notions
Flavio Corradini, Chiara Muzi, Barbara Re and Francesco Tiezzi
Persistent Stochastic Non-Interference
Jane Hillston, Carla Piazza and Sabina Rossi
Reversing Parallel Programs with Blocks and Procedures
James Hoey, Irek Ulidowski and Shoji Yuen
A Parametric Framework for Reversible Pi-Calculi
Doriana Medic, Claudio Antares Mezzina, Iain Phillips and Nobuko Yoshida
On the Distributability of Mobile Ambients
Kirstin Peters and Uwe Nestmann
Unique Solutions of Contractions, CCS, and their HOL Formalisation
Chun Tian and Davide Sangiorgi


This volume contains the proceedings of the Combined 25th International Workshop on Expressiveness in Concurrency and the 15th Workshop on Structural Operational Semantics (EXPRESS/SOS 2018), which was held on September 3, 2018, in Beijing, China, as an affiliated workshop of CONCUR 2018, the 29th International Conference on Concurrency Theory.

The EXPRESS workshops aim at bringing together researchers interested in the expressiveness of various formal systems and semantic notions, particularly in the field of concurrency. Their focus has traditionally been on the comparison between programming concepts (such as concurrent, functional, imperative, logic and object-oriented programming) and between mathematical models of computation (such as process algebras, Petri nets, event structures, modal logics, and rewrite systems) on the basis of their relative expressive power. The EXPRESS workshop series has run successfully since 1994 and over the years this focus has become broadly construed.

The SOS workshops aim at being a forum for researchers, students and practitioners interested in new developments, and directions for future investigation, in the field of structural operational semantics. One specific goal of the SOS workshop series is to establish synergies between the concurrency and programming language communities working on the theory and practice of SOS. Reports on applications of SOS to other fields are also most welcome, including: modeling and analysis of biological systems, security of computer systems programming, modeling and analysis of embedded systems, specification of middle-ware and coordination languages, programming language semantics and implementation, static analysis software and hardware verification, semantics for domain-specific languages and model-based engineering.

Since 2012, the EXPRESS and SOS communities have organized an annual combined EXPRESS/SOS workshop on the expressiveness of mathematical models of computation and the formal semantics of systems and programming concepts.

This volume contains eight papers selected by the program committee for publication and presentation at the workshop. The workshop program included also two invited presentations:

We would like to thank the authors of the submitted papers, the invited speakers, the members of the program committee, and their sub-reviewers for their contribution to both the meeting and this volume. We also thank the CONCUR 2018 organizing committee for hosting EXPRESS/SOS 2018. Finally, we would like to thank our EPTCS editor Rob van Glabbeek for publishing these proceedings and his help during the preparation.

Jorge A. Pérez and Simone Tini, August 2018

Program Committee

Pedro D'Argenio (Universidad Nacional de Córdoba, Argentina)
Erik De Vink (Eindhoven University of Technology, The Netherlands)
Ignacio Fabregas (IMDEA Software Institute, Spain)
Mohammad Mousavi (University of Leicester, UK)
Jurriaan Rot (Radboud University, The Netherlands)
Cinzia Di Giusto (Université Côte d'Azur, France)
Simon Gay (University of Glasgow, UK)
Vasileios Koutavas (Trinity College Dublin, Ireland)
Bas Luttik (Eindhoven University of Technology, The Netherlands)
Claudio Mezzina (IMT School for Advanced Studies, Italy)
Jorge A. Pérez (University of Groningen, The Netherlands)
Simone Tini (University of Insubria, Italy)
Valeria Vignudelli (CNRS/ENS Lyon, France)

Additional Reviewers

Maciej Gazda
Mathias Ruggaard Pedersen

On Milner's Axiomatization for Regular Expressions

Wan Fokkink (Vrije Universiteit Amsterdam)

In 1984, Robin Milner formulated an axiomatization for regular expressions in bisimulation semantics. It is still an open question whether this axiomatization is ground-complete. I will explain some ideas behind an ongoing attempt to provide an affirmative answer to this question.

Adventures in Monitorability

Adrian Francalanza (University of Malta)

Runtime Verification is a lightweight technique that checks at runtime whether a program satisfies (or violates) a correctness property. It synthesises monitors from properties specified in some formal logic, which are then instrumented to run alongside the executing program so as to analyse its behaviour and flag detected satisfactions or violations. The joint research group at Reykjavik University and the University of Malta has been challenging the commonly held assumption that only linear-time properties can be monitored at runtime. In particular, the group has established maximality results for the monitorability of the modal mu-calculus with a branching-time interpretation. These results, however, remain quite disconnected from the rich theory of linear-time monitoring that has been developed over the years. In this presentation I will overview ongoing work that aims to bridge this gap. By considering a linear-time interpretation of modal mu-calculus, this study extends the methods used for the branching-time setting to establish missing results on the path towards a unified theory of monitorability.