[Apologies for multiple postings]

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FIRST CALL FOR PAPERS - EXPRESS/SOS 2026

Combined 33rd International Workshop on Expressiveness in Concurrency
and 23rd Workshop on Structural Operational Semantics (Express/SOS 2026)

September 5, 2026, Liverpool, UK
Affiliated with CONFEST 2026

https://expresssos.github.io/conf/2026

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IMPORTANT DATES (AoE)

- Paper Submission: June 22, 2026
- Notification: July 25, 2026
- Workshop: September 5, 2026
- Final version (post-proceedings): October 25, 2026

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SCOPE AND TOPICS

The Express/SOS workshop series aims to bring together researchers interested in the formal semantics of systems and programming concepts, and in the expressiveness of computational models.

Topics of interest for Express/SOS 2026 include, but are not limited to: 
- expressiveness and rigorous comparisons between models of computation (process algebras, event structures, Petri nets, rewrite systems);
- expressiveness and rigorous comparisons between programming languages and models (distributed, component-based, object-oriented, service-oriented);
- logics for concurrency (modal logics, probabilistic and stochastic logics, temporal logics and resource logics);
- analysis techniques for concurrent systems;
- theory of structural operational semantics (meta-theory, category-theoretic approaches, congruence results);
- comparisons between structural operational semantics and other formal semantic approaches;
- applications and case studies of structural operational semantics;
- software tools that automate, or are based on, structural operational semantics.

We especially welcome contributions bridging the gap between the above topics and neighbouring areas, including:

- computer security
- multi-agent systems
- programming languages
- formal verification
- reversible computation
- knowledge representation

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INVITED SPEAKERS

TBA

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SUBMISSION GUIDELINES

We invite two types of submissions:

- Full papers (up to 15 pages, excluding references)
- Short papers (up to 5 pages, excluding references, not to be included in the workshop post-proceedings)

All submissions must adhere to the EPTCS format (https://info.eptcs.org/).
Simultaneous submission to journals, conferences, or other workshops is only allowed for short papers; full papers must be unpublished.

Submission is performed through EasyChair:
https://easychair.org/conferences/?conf=expresssos2026

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PROCEEDINGS

The final versions of accepted full papers will be published in EPTCS.
For each accepted paper, at least one of the co-authors must register and present the work at the workshop.

* We are planning a Joint Special Issue with Express/SOS 2025 (due in December 2026).

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WORKSHOP CO-CHAIRS

- Giorgio Bacci (University of Aalborg, Denmark)
- Anna Philippou (University of Cyprus, Cyprus)

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PROGRAM COMMITTEE

- Henning Basold (LIACS, Leiden University, NL)
- Giovanni Bernardi (Université Paris Diderot - IRIF, FR)
- Marco Bernardo (University of Urbino, IT)
- Chiara Bodei (University of Pisa, IT)
- Johannes Borgström (Uppsala University, SE)
- Georgiana Caltais (University of Twente, NL)
- Pedro R. D'Argenio (Universidad Nacional de Córdoba - CONICET, AR)
- Emanuele D'Osualdo (University of Konstanz, DE)
- Fatemeh Ghassemi (University of Tehran, IR)
- David N. Jansen (Institute of Software, Chinese Academy of Sciences, CN)
- Vasileios Koutavas (Trinity College Dublin, IE)
- Dimitrios Kouzapas (University of Cyprus, CY)
- Doriana Medić (University of Turin, IT)
- Luca Padovani (University of Bologna, IT)
- Jovanka Pantovic (University of Novi Sad, RS)
- Marco Peressotti (University of Southern Denmark, DK) 
- Jorge A. Pérez (University of Groningen, NL)

- Tatjana Petrov (University of Trieste, IT) 
- Emilio Tuosto (Gran Sasso Science Institute, IT)

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CONTACT

For inquiries, please contact the co-chairs:
grbacci@cs.aau.dk
annap@ucy.ac.cy