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The 10th IFIP WG 1.8 Workshop on Trends in Concurrency Theory

August 28, 2021, Online

A satellite event of QONFEST 2021



TRENDS 2021 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 August 28, 2021 and will consist of three invited talks. It will be associated with the yearly WG 1.8 business meeting.

Invited Speakers

  • Christel Baier, Technische Universität Dresden, DE

    Title: From verification to causality-based explications

    The early success story of the model checking approach relies fundamentally on two features. First, the algorithms provide a push-button technology: As soon as the model and specification have been generated, one obtains a result in a fully automated way. Second, if the algorithm terminates with a negative result, then it can infer counterexamples to the specification. Counterexamples are the first instances for what we use the term explication, which refers to a mathematical concept that in some way sheds light on why the model checker has returned the result. While counterexamples are single instances of execution traces violating the specification, they provide little insights in what causes the specification violation. To enhance the system transparency, more crisp explications for the satisfaction or violation of properties are demanded. The talk presents an overview of techniques that go in this direction by using formal notions of causality and responsibility to explicate verification results.

  • Alexey Gotsman, IMDEA Software Institute, SP

    Title: Rigorous Design of Atomic Transaction Commit Protocols

    Modern data stores often need to provide both high scalability and strong transactional semantics. They achieve scalability by partitioning data into shards and fault tolerance by replicating each shard across several servers. A key component of such systems is the protocol for atomically committing a transaction spanning multiple shards. Unfortunately, existing data stores entangle atomic commit protocols with the rest of the system and lack proofs of their correctness. On the other hand, the classical theory of atomic commit is too restrictive to capture the complexities of modern protocols. To fill this gap, I will present a new problem statement for atomic commit that more faithfully reflects modern requirements and will describe an efficient and provably correct solution to this problem. I will also explain how these results enable more modular and rigorous design of transactional data stores.

  • Ilaria Castellani, INRIA, FR

    Title: Event structure semantics for asynchronous multiparty sessions

    Session types have been an active trend of research for more than two decades. They are associated with session calculi, which are process calculi tailored to describe structured interactions among two or more parties. The aim of session types is to specify the structure of process interaction and to ensure classical properties of this interaction, such as deadlock-freedom.

    Session calculi are usually given an operational semantics by means of an LTS or a reduction relation. In recent work with Mariangiola Dezani and Paola Giannini, we proposed a denotational semantics by means of Event Structures (ESs) for a core multiparty session calculus. We considered both synchronous and asynchronous communication: in both cases we defined an interpretation of multiparty sessions as Flow ESs and an interpretation of their types (when defined) as Prime ESs. The latter requires the causality relation to be extracted from an equivalence class of traces, since types are sequential specifications. We showed that when a session is typable, its Flow ES and the Prime ES of its type yield isomorphic domains of configurations.

    In the talk I will focus on the asynchronous case, which is more novel in two respects: we provide an ES semantics for an asynchronous calculus, and we introduce new types for asynchronous multiparty sessions, which we call asynchronous types. Our new typing is more permissive than the original typing for asynchronous sessions, while remaining decidable.


14:00-14:15 - Opening

14:15-15:15 - Invited Talk: Christel Baier. “From verification to causality-based explications”

15:15-15:45 - Break

15:45-16:45 - Invited Talk: Alexey Gotsman. “Rigorous Design of Atomic Transaction Commit Protocols”

16:45-17:00 - Break

17:00-18:00 - Invited Talk: Ilaria Castellani. “Event structure semantics for asynchronous multiparty sessions”

18:00-19:00 - IFIP WG 1.8 Business meeting


Participation, both to the workshop and to the IFIP WG 1.8 meeting, is open to everybody. For registration, please consult the QONFEST 2021 registration 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