Discrete Event Systems

Virtual Talk Series 2023


The IEEE CSS TC DES is organizing a Virtual Talk Series on Discrete Event Systems throughout 2023. In order to access past talks, you will need to register on the page below under "Registration."

Date & Time:

The talks take place virtually via Zoom on the 3rd Thursday of each month in 2023 (March, July, August, December) at 13:00 UTC (Paris 14:00, New York City 8:00, Beijing 21:00). Please see the detailed schedule below.

Particularly, in January and February the VTS will feature a Virtual Workshop on Control Software Synthesis for CPS happening Wednesdays, January 18th 2023 and February 15th 2023 at 1pm UTC.


Registration is free. For security reasons we require pre-registration. Participants will receive log-in details to the virtual zoom meeting after registration.

register now!




January 18 | 13:00 UTC

IEEE CSS TC DES Virtual Workshop on Control Software Synthesis for CPS (Part 1)

Talk 1: Compositional synthesis using the least-violating control framework
Presenter: Antoine Girard (L2S – CentraleSupélec, France)
Talk 2: Unified Bisimulation for Compositional Verification, Synthesis and Time Optimization.
Presenter: Bengt Lennartson (Chalmers University of Technology, Sweden)
Talk 3: Compositional verification and synthesis of interconnected control systems Presenter: Majid Zamani (University of Colorado, Boulder, United States)

For more information about the speakers and the talks please visit the workshop website: https://css-workshop-23.mpi-sws.org/talks/

Antoine Girard

CNRS, Centrale Supelec

Bengt Lennartson

Chalmers University of Technology

Majid Zamani

University of Colorado, Boulder
United States
February 15 | 13:00 UTC

IEEE CSS TC DES Virtual Workshop on Control Software Synthesis for CPS (Part 2)

Talk 1: Probabilistic Hyperproperties of Markov Decision Processes: Information-Flow Properties and Beyond
Presenter: Rayna Dimitrova (CISPA Helmholtz Center for Information Security, Germany)
Talk 2: A Unified Framework for Verification of Observational Properties for Partially-Observed Discrete-Event Systems
Presenter: Xiang Yin (Shanghai Jiao Tong University, China)

For more information about the speakers and the talks please visit the workshop website: https://css-workshop-23.mpi-sws.org/talks/

Rayna Dimitrova

CISPA Helmholtz Center for Information Security

Xiang Yin

Shanghai Jiao Tong University
March 2023

Spring Break

No Event Scheduled

April 20 | 13:00 UTC

PhD Students Forum

Talk 1: Synthesis of Decentralised Supervisory Control via Contract Negotiation
Presenter: Ana Mainhardt (Max Planck Institute for Software Systems, Germany)
Abstract: In this talk, I will present a method for the synthesis of local supervisors for decentralised discrete event systems where subsystems may have different controllability settings for their shared events, and where the privacy of the local nonshared events plays a vital role. Our approach is based on the negotiation of contracts represented solely over these shared events and describing an agreement between the subsystems, such that they cooperate in disabling events in order to guarantee their local specifications are satisfied. We establish further conditions to ensure correct cooperation and global nonblockingness, which are locally checked and, if necessary, enforced. This way, both during synthesis and execution, the dynamics of a subsystem are only partially observed by others through the events they actually share, without the communication of exclusively local events or the use of a coordinator for their supervisors. We identify the cases where maximal permissiveness can be achieved by our approach; otherwise, it is sacrificed in order to protect privacy.

Talk 2: Max-plus algebra for scheduling and control of manufacturing systems with time-window constraints 
Presenter: Davide Zorzenon (Technische Universität Berlin, Germany)
Abstract: Time-window constraints show up in several industrial settings. Two examples are the baking and printed circuit boards industries, where both insufficient and excessive durations of some processes (e.g., yeast fermentation in the former case, metal deposition in the latter) can irreparably damage the final product. The presence of temporal upper-bound constraints makes the scheduling task in these systems particularly challenging as, counterintuitively, machines may be required to work at reduced pace to avoid constraint violations. The aim of this presentation is to discuss the application of max-plus algebraic methods for (open-loop) scheduling and (closed-loop) control of manufacturing systems with time-window constraints. I will first focus on the computation of two important performance indices: makespan and throughput. In the max-plus algebra, these quantities admit closed-form expressions, resulting in algorithms of lower computational complexity compared to standard techniques based on linear programming or graph theory. In the second part of the talk, I will address the following question: how to control the system such that no temporal constraint violations occur, despite the presence of unforeseeable delays? 

Ana Mainhardt

Max Planck Institute for Software Systems

Davide Zorzenon

Technische Universität Berlin
May 25 | 13:00 UTC

Infinite-state DES with Partial Observation: Modelling, Analysis and Control


We propose a mathematical setting where traditional problems on DES under partial observation can be addressed as a model-checking problem over an infinite-state DES in a very natural way, and in particular as a first-order logic model-checking problem. We will then discuss hypothesis on the kind of partial observation that are amenable to developing various tools for those traditional problems. At a theoretical level, we can establish remarkable properties of the set of solutions (e.g. the effective regularity of the set of solutions), and at a more practical level, how to use the setting to design alternative algorithms for solution synthesis.

Sophie Pinchinat

University of Rennes
June 15 | 13:00 UTC

Set-membership State Estimation of Max-plus Linear Systems by Using Tropical Polyhedral


Max-plus algebra is suitable to model dynamical discrete event systems. The occurrence date of events is chosen as the state of the system. The state estimation consists in computing the occurrence date of internal events (hidden states) thanks to output measurements and previous states knowledge. The system is assumed to be uncertain, more precisely, its parameters are supposed to be random values belonging to an interval. The talk will compare the different ways to estimate the system state in this uncertain context by considering set-membership approach which can be based on interval analysis, difference bound matrices or max-plus polyhedra. It will be organized as follows : First, linear max-plus systems will be presented and the synthesis of an observer (inspired by the Luenberger observer) allowing an online estimation to be given, then its performance will be analyzed. Then, the scheme of a state filtering approach based on a prediction step and a correction step (inspired by Bayes filtering) will be introduced. Interval analysis will first be considered to implement this filtering, we will show that the set of states obtained contains the real states in a guaranteed way. It is obtained with polynomial complexity, but provides an over approximation of the states set. The difference bound matrices will be then introduced and used to obtain the reachable set (in which the prediction belongs) and the estimated set. This estimated set is the exact set in the sense that all the reachable set under the measurement constraints is depicted, but this filter is with an exponential complexity. The max-plus polyehdra is last considered, it will lead also to the exact set of possible states. It reduces the complexity especially in the prediction step. The tropical polyhedra library (TPL) will be used to implement this filter. The talk will conclude by providing examples to illustrate the results.

Laurent Hardouin

University of Angers
July 2023

IFAC 2023

No Event Scheduled

August 2023

Summer Break

No Event Scheduled

September 14 | 13:00 UTC

On Distributed Synthesis


Automated synthesis of distributed systems has a big potential since manually designing such systems is often quite challenging. However, since the early work of Pnueli and Rosner distributed synthesis acquired the reputation of being genuinely intractable. Very recently, distributed synthesis with causal memory was shown by H. Gimbert to be undecidable as well. The talk will present related results, and show some recent decidability results about the synthesis of distributed systems that synchronise using locks.

Anca Muscholl

Université Bordeaux
October 19 | 13:00 UTC

Optimizing Multi-Agent Systems based on DES and Structural Analysis


During this session, we will unveil powerful solutions for addressing the complex challenge of high-level path planning in multi-agent systems. Our approach leverages Linear Temporal Logic (LTL) formulas to define mission specifications for teams of agents, which are then seamlessly translated into Buchi automata, encompassing all possible solutions. Discover not one, but two distinct strategies. First, we'll explore a method that involves the computation of a string within the Buchi automaton, which the team model defined as a Petri net endeavors to generate. Secondly, we'll delve into the fusion of the team and specification models, culminating in the resolution of planning dilemmas on a larger scale. This talk will also feature a comprehensive comparison between these two innovative approaches and a third method grounded in transition systems.

Cristian Mahulea

University of Zaragoza
November 16 | 13:00 UTC

Hierarchical and Modular Supervisory Control Under Partial Observations


Conditions preserving observability of specifications between the plant and its abstraction are essential for hierarchical supervisory control of discrete-event systems under partial observation. Observation consistency is such a condition preserving normality between the levels for normal specifications. However, for specifications that are not normal, observation consistency is insufficient to guarantee that the supremal normal sublanguage computed on the low level and on the high level coincide. We defined the notion of modified observation consistency (MOC), under which the supremal normal sublanguages of different levels coincide, and showed that the verification of MOC as well as of observation consistency (OC) is PSPACE-hard for finite automata and undecidable for slightly more expressive models than finite automata. Decidability of (M)OC is an open problem. We further discuss two stronger conditions that are easy to verify, and the applications of MOC in modular supervisory control. Finally, we illustrate the conditions on a case study of a part of an MRI scanner. (Joint work with J. Komenda.)

Tomas Masopust

Palacky University in Olomouc
December 2023

CDC 2023

No Event Scheduled