The (i)Po(m)set Project is a research project at the crossroads of concurrency theory, automata theory, algebra, and geometry. You are at the page of its online seminar.


The seminar is organized by Uli Fahrenberg, Christian Johansen and Krzysztof Ziemiański and takes place on zoom. If you want to participate, send an email to ppos-owner@ml.lre.epita.fr so that we can add you to our mailing list. You will receive about one email per week in average: seminar announcements, reminders, and the zoom link.

Talks generally last at most one hour, including time for questions.

Upcoming Talks

See also the seminar's google calendar.

Friday 31 May 2024 11:00 CEST

Michał Gajda, Migamake Pte Ltd, Singapore: Decomposition of countable semigroups and simplex languages

Krohn-Rhodes decomposition theorem for finite semigroups facilitates many other results. It has been so far generalized to residually finite semigroups. We use the definition of archimedean semigroups together with generalization of multiples to propose a further generalization to decompose any countable semigroups. We then examine the behaviour of this generalization, by characterizing languages corresponding to arbitrary countable semigroups, and proposing a geometric generalization of regular expressions that provides a useful computable characterization of many such languages.
The work includes a definition of Countable HDA proposed by Krzysztof Ziemiański.

Friday 14 June 2024 11:00 CEST

Clovis Eberhart, National Institute of Informatics, Tokyo, Japan: TBA

Friday 28 June 2024 11:00 CEST

Ichiro Hasuo, National Institute of Informatics, Tokyo, Japan: TBA


Workshop on Pomsets and Related Structures (RaPS), Rennes, 24 April 2024.

Previous Talks in 2024

Friday 17 May 2024 11:00 CEST

Anca Muscholl, LaBRI, Université Bordeaux, France: On partial-order and automata techniques for analysing communication

Friday 5 April 2024 11:00 CEST

Fabio Gadducci, Università di Pisa, Italy: The algebraic view of concatenable net processes

Friday 15 March 2024 11:00 CET

Paul-André Melliès, CNRS, Université Paris Cité, INRIA, France: The rabbit calculus: convolution products on double categories and categorification of rule algebra


Friday 1 March 2024 11:00 CET

Henning Basold, Universiteit Leiden, The Netherlands: Towards higher coalgebra: the enriched case

Slides; Slides, annotated

Friday 16 February 2024 11:00 CET

Uli Fahrenberg, LRE, Rennes/Paris, France: Generating posets with interfaces

Friday 19 January 2024 11:00 CET

Thomas Kahl, Universidade do Minho, Braga, Portugal: Weak equivalence of higher-dimensional automata

Previous Talks in 2023

Friday 12 January 2024 10:30 CET

Mikołaj Bojańczyk, University of Warsaw, Poland: About recognisability of graph languages

Friday 1 December 2023 11:00 CET

Roman Kniazev, IRIF, Paris, France: Simplicial models for epistemic logic (sprinkled with concurrency)

Friday 17 November 2023 11:00 CET

Amar Hadzihasanovic, TalTech, Tallinn, Estonia: The homotopy posets of a category

Friday 3 November 2023 11:00 CET

Rob van Glabbeek, University of Edinburgh, Scotland: Translating Petri nets to higher-dimensional automata

Friday 20 October 2023 11:00 CEST

Łukasz Mikulski, NCU, Toruń, Poland: Relational structures for interval order semantics of concurrent systems

Friday 6 October 2023 11:00 CEST

Matt Earnshaw, TalTech, Tallinn, Estonia: Monoidal languages

Friday 15 September 2023 11:00 CEST

Matteo Acclavio, SDU, Odense, Denmark: The proof theory of pomsets

Friday 1 September 2023 11:00 CEST

Loïc Hélouët, IRISA, Rennes, France: Waiting nets

Friday 18 August 2023 11:00 CEST

Jérémy Dubut-Kross, AIST, Tokyo, Japan: Bisimulations and unfolding in P-accessible categorical models

Friday 14 July 2023 11:00 CEST

Marie Fortin, IRIF, Paris, France: Logics and automata for Message Sequence Charts

Friday 16 June 2023 11:00 CEST

Tobias Kappé, Open Universiteit, The Netherlands: Completeness and the finite model property for Kleene algebra, reconsidered

Friday 19 May 2023 11:00 CEST

Amazigh Amrane, EPITA Paris, France: Series-parallel pomsets: automata and logic

Friday 14 April 2023 11:00 CEST

Sergio Rajsbaum, UNAM, Mexico and IRIF, Paris, France: Unifying concurrent objects and distributed tasks: interval-linearizability

Friday 17 March 2023 11:00 CET

Safa Zouari, NTNU Gjøvik, Norway: Logical characterization of hh-bisimulation via open maps for HDA