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The 12th IFIP WG 1.8 Workshop on Trends in Concurrency Theory

September 23, 2023, Antwerp, Belgium

A satellite event of CONFEST 2023


TRENDS 2023 is an event organised by IFIP WG 1.8 on Concurrency Theory. It aims at bringing together researchers interested in Concurrency Theory and its applications, to exchange ideas and discuss recent trends and open problems. The event will take place on September 23, 2023. It will be associated with the yearly WG 1.8 business meeting.

Invited Speakers

  • Azalea Raad, Imperial College London, UK

    Title: Principles of Persistent Programming

    Persistent programming is the art of developing programs that operate on persistent (non-volatile) states that survive program termination, be it planned or abrupt (e.g. due to a power failure). Persistent programming poses several important challenges: 1) persistent systems have complex—and often unspecified—semantics in that operations do not generally persist in their execution order; 2) software bugs in persistent settings can lead to permanent data corruption; and 3) traditional testing techniques are inapplicable in persistent settings. Can formal methods come to the rescue?

  • Marco Bernardo, Università di Urbino, IT

    Title: A Process Algebraic Theory of Reversible Systems

    Reversibility is the capability of a system of undoing its own actions starting from the last performed one, in such a way that a past consistent state is reached. This is not trivial for concurrent systems, as the last performed action may not be uniquely identifiable. There are several approaches to address causality-consistent reversibility, some including a notion of forward-reverse bisimilarity. We present a minimal process calculus for reversible sequential systems – so as to be neutral with respect to interleaving vs. truly concurrent semantics of parallel composition – on which we investigate compositionality properties, axiomatizations, and modal logic characterizations of forward-reverse bisimilarity as well as of its two components, i.e., forward bisimilarity and reverse bisimilarity, both in the strong case and in the weak case.

  • Simona Ronchi Della Rocca, Università di Torino, IT

    Title: Intersection and Simple types

    When, in the seventies of the last century, Coppo and Dezani designed intersection types, their main motivation was to extend the typability power of simple types, adding them an intersection connective, enjoying associativity, commutativity and idempotency, so denoting set formation. In fact, the simple types system can be seen as a restriction of the intersection type system where all sets are singletons. Quite early intersection types turned out to be useful in characterizing qualitative properties of λ-calculus, like solvability and strong normalization, and in describing models of λ-calculus in various settings. A variant of intersection types, where the intersection is no more idempotent, has been recently used to explore quantitative properties of programming language, like the length of the normalisation procedure. It is natural to ask if there is a quantitative version of the simple type system, or more precisely a decidable restriction of non-idempotent intersection system with the same typability power of simple types. Since the lack of idempotency, now the intersection corresponds to multiset formation, so (extending the previous reasoning) the natural answer is to restrict the multiset formation to copies of the same type. But this answer is false, the so obtained system is decidable, but it has less typability power than simple types. We prove that the desired system is obtained by restricting the multiset formation to equivalent types, where the equivalence is an extension of the identity, modulo the cardinality of multisets.

  • Uwe Nestmann, TU Berlin, DE

    Title: The Way to Go?

    Concurrent/distributed programming is ubiquitous nowadays. Despite the many results and insights of Concurrency Theory over the last decades, there is still a (too) large gap between theory and applications. This talk addresses possibilities and experiences to bridge this gap in the area of (more or less) mainstream programming languages, looking at it from a process calculus perspective.


8:50-9:00. Opening

9:00-10:00. Simona Ronchi Della Rocca. “Intersection and Simple types”

10:00-10:20. Coffee Break

10:20-11:20. Uwe Nestman. “The Way to Go?”

11:20-12:20. Marco Bernardo. “A Process Algebraic Theory of Reversible Systems”

12:20-13:45. Lunch Break

13:45-14:45. Azalea Raad. “Principles of Persistent Programming”

14:45-15:45. IFIP WG 1.8 Business meeting

15:45-16:00. Coffee Break


Participation, both to the workshop and to the IFIP WG 1.8 meeting, is open to everybody. For registration, please consult the CONFEST 2023 home page.


Pedro R. D’Argenio (Universidad Nacional de Córdoba, Argentina)

Ana Sokolova (University of Salzburg, Austria)

IFIP WG 1.8 on Concurrency Theory

The aims of IFIP WG 1.8 on Concurrency Theory are:

  • To develop theoretical foundations of concurrency, exploring frontiers of existing theoretical models like process algebra and process calculi, so as to obtain a deeper theoretical understanding of concurrent and parallel systems.

  • To promote and coordinate the exchange of information on concurrency theory, by sharing ideas, discussing open problems, and identifying future directions of research in the area.

The activities of this WG encompass all aspects of concurrency theory and its applications.

More information on IFIP WG 1.8 can be found on its home page.


The first instalment of TRENDS (TRENDS 2012) was held on September 8, 2012 as a satellite event of CONCUR 2012, in Newcastle upon Tyne, UK.

The second instalment of TRENDS (TRENDS 2013) was held on August 31, 2013 as a satellite event of CONCUR 2013, in Buenos Aires, Argentina.

The third instalment of TRENDS (TRENDS 2014) was held on September 6, 2014 as a satellite event of CONCUR 2014, in Rome, Italy.

The fourth instalment of TRENDS (TRENDS 2015) was held on September 6, 2015 as a satellite event of CONCUR 2015, in Madrid, Spain.

The fifth instalment of TRENDS (TRENDS 2016) was held on August 27, 2016 as a satellite event of CONCUR 2016, in Quebec City, Canada.

The sixth instalment of TRENDS (TRENDS 2017) was held on September 9, 2017 as a satellite event of CONCUR 2017, in Berlin, Germany.

The seventh instalment of TRENDS (TRENDS 2018) was held on September 8, 2018 as a satellite event of CONCUR 2018, in Beijing, China.

The eighth instalment of TRENDS (TRENDS 2019) was held on August 31, 2019 as a satellite event of CONCUR 2019, in Amsterdam, The Netherlands.

The ninth instalment of TRENDS (TRENDS 2020) was held on September 5, 2020 as a satellite event of CONCUR 2020, in Vienna, Austria Online.

The tenth instalment of TRENDS (TRENDS 2021) was held on August 28, 2021 as a satellite event of CONCUR 2021, in Paris, France Online.

The eleventh instalment of TRENDS (TRENDS 2022) was held on September 12, 2022 as a satellite event of CONCUR 2022, in Warsaw, Poland.