Discrete Event Systems

Virtual Talk Series 2022


The IEEE CSS TC DES is organizing a Virtual Talk Series on Discrete Event Systems throughout 2022 to enhance communications in our community during the current Covid-19 pandemic. 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 2022 (except August, September, December) at 13:00 UTC (Paris 14:00, New York City 8:00, Beijing 21:00). Please see the detailed schedule below.


This year we will organize a variety of events of different forms. The main focus remains talks on cutting-edge topics. In addition, we will hold a panel discussion, a PhD student forum, and talks by authors of recent top journal papers.


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 20 | 13:00 UTC

Event-Based Reinforcement Learning for Cyber-Physical Energy Systems – Smart Buildings, Smart Grid, and Smart Cities


Cyber physical energy system (CPES) is where information and energy merges together to improve the overall system performance including economic, comfort, and safety aspects. Artificial intelligence which are enabled by internet of things, big data, and cloud computing, has a big role in the optimization of CPES. In this talk, we focus on event- based reinforcement learning (eRL) which makes decisions according to events instead of states. This method provides a scalable solution for large-scale multi-stage decision making problem in which an accurate model may not be available. The performance of this method will be demonstrated by examples in smart buildings, smart micro-grid of buildings, and smart cities, and in particular on the problem of stochastic matching between the renewable power generation and the uncertain charging demand from the plug-in electric vehicles (PHEVs) in a city. We will also discuss extensions of this method to distributed optimization. We hope this work sheds light to the optimization of CPES.

Qing-Shan (Samuel) Jia

Tsinghua University
February 17 | 13:00 UTC

Talk canceled

March 17 | 13:00 UTC

Fast, Optimal, and Guaranteed Control Synthesis for Autonomous Robots


Rigorous approaches based on formal methods can generate correct-by-construction plans and controllers. By reducing designing and testing cycles, formal synthesis can help create safe autonomous robots that involve complex interactions of dynamics and decision logic. In general, however, synthesis problems are known to have high computational complexity for high dimensional, nonlinear systems and complex tasks. In this talk, I will present a new synthesis approach that suggests that these challenges can be overcome and that rigorous approaches are indeed promising. I will talk about how to synthesize plans and controllers for autonomous systems that are nonlinear, hybrid, multi-agent, and need to follow temporal logic specifications, with guarantees on the safety and optimality of the solutions.

Chuchu Fan

Massachusetts Institute of Technology
United States
April 21 | 13:00 UTC

Panel Discussion on DES Tools/Applications

Panelists and software:

1. Martin Fabian
Chalmers University of Technology

2. Lucas Alves
Universidade Federal de Minas Gerais

3. João Carlos Basilio
Universidade Federal do Rio de Janeiro

4. Renyuan Zhang
Northwestern Polytechnical University

5. Rômulo Meira-Góes 
Carnegie Mellon University 

6. Dennis Hendriks
ESI (TNO) and Radboud University Nijmegen

May 19 | 13:00 UTC

Applications of Untimed SCT to Scheduling Problems


In industry, performance must be optimized to allow its competitiveness. Optimization is applied in industry aiming to improve its production performance by using resources at their maximal capacity, by reducing the production time, by making the production flexible to adapt to customer’s requests, among other possible objectives. In the optimization community, the modeling of restrictions is a well-known difficult problem. The integration of optimization methods with the (classical untimed) Supervisory Control Theory is a viable approach to solve scheduling problems in manufacturing systems. The role of the supervisory control theory is to provide the set of all safe production sequences (the restrictions), given by the closed-loop behavior under control. Such behavior becomes the search space of the optimization problem. We will discuss in this talk the work that has been done with classical untimed SCT to assist the solution of makespan optimization in manufacturing systems.

Patrícia Nascimento Pena

Universidade Federal de Minas Gerais
June 23 | 13:00 UTC

Using Reactive Synthesis on Discrete Event Systems


About 35 years ago two landmark results established two related research fields that remained isolated from each other for a very long time. In the first, Peter Ramadge and Walter (Murray-)Wonham established supervisory control theory. In the second, establishing the field I come from, Amir Pnueli and Roni Rosner modernized Church's synthesis problem to Linear Temporal Logic.

In spite of connections between the two fields discovered relatively early on (notably, John Thistle’s PhD work), both fields developed their respective (related) techniques building on different traditions. In 2017, (some of the) leaders of both research fields joined forces and wrote a landmark paper comparing the two approaches and how to translate between them.

In this talk, I will survey some of their conclusions about the connections between the two fields and present some of my own results
on applications of reactive synthesis on discrete event systems. My interest in this line of work arose from applications in software engineering (particularly requirements engineering) and adapting reactive-synthesis algorithms to be used in this domain and for
problems that arise in this domain. I will survey the change from GR[1] to SGR[1], the insights that accompanied this adaptation, some of the current usage (by collaborators) of these synthesis techniques, extensions of synthesis to modal discrete event systems, and its usage for exploration.

Nir Piterman

Chalmers University of Technology
July 21 | 13:00 UTC

PhD Students Forum

Talk 1

Infinitesimal Perturbation Analysis for the perimeter control problem in a Two-Region Urban Transportation Network utilizing a Macroscopic Fundamental Diagram


Traffic congestion in big cities has been proven to be a di cult problem with sub-optimal effects in terms of driver delay, frustration cost, and impact on the environment. In principle, many transportation networks lack a unified framework, which will coordinate the traffic in such a manner, aiming to suppress the congestion, and improving the travel time of the users commuting inside it. In view of this inadequacy, we consider the perimeter control problem for a two urban region abstracted as a stochastic hybrid system (SHS). The dynamics of each region are dictated by a Macroscopic Fundamental Diagram (MFD), in which the behavior of the system is partitioned into four different modes of operation, based on the value of density affiliated with each region situated above or below its critical density. We employ a framework known as Infinitesimal Perturbation Analysis (IPA) to dynamically adjust the controllable parameters of interest, by deriving online gradient estimators of a cost metric (i.e. maximization of the throughput of vehicles). Essentially, the SHS setting transcribes the network into a Discrete Event System (DES). The power of IPA lies within its data-driven nature to identify discontinuities in the state dynamics which subsequently signify the occurrence of an event. These estimators are used to adjust the control vector of interest iteratively through a stochastic gradient-based algorithm to maximize the system's performance. Treating the critical density of each region as a known parameter, through this framework, we aim to pinpoint the percentage of flow that traverses the "ego" region with destination to its adjacent one and vice versa to optimize the cumulative portion of vehicles that exits from each region. In comparison with other approaches, where brute force algorithms are employed to designate the optimal values of the control parameters, (IPA) anticipates the impact of events utilizing the "perturbation propagation" term and provides an estimate of the gradient without having prior knowledge of the underlying graph of the system. The novel feature in this work is the modeling architecture perceived, enabling us to capture the "perturbation propagation" when non-linearity between the interconnected regions arises due to the capacity constraints activated at the boundaries of the two regions.

Antonios Georgantas

University of Cyprus
Talk 2

Obfuscation and Inference: Enforcing Opacity and Utility


With growing concerns over the privacy of networked systems, many mechanisms for enforcing opacity as a form of privacy have been developed. In particular, obfuscating a system's outputs can preserve privacy when it is unfeasible to restrict a system's behavior. However, privacy must also be balanced with the oftentimes conflicting goal of utility. Specifically, observations of the system must reveal secrets to intended recipients while hiding them from unintended ones. In this talk, I will discuss a new framework for the obfuscation of discrete event systems and inference of intended recipients. Modeling these processes as a distributed system, I will show how utility and notions of opacity, including K-step opacity, can be formulated as temporal specifications.

Leveraging techniques from distributed reactive synthesis, I will then present how both an obfuscator for the system and inference process used by the intended recipients can be synthesized..

Andrew Wintenberg

University of Michigan
United States

No event during summer break


No event due to WODES 2022

October 20 | 13:00 UTC

Polynomial-Time Optimal Liveness Enforcement for Guidepath-Based Transport Systems


Guidepath-based transport systems is a popular abstraction for many contemporary applications, from the Automated Guided Vehicle (AGV) systems and the overhead monorail systems that are used in many industrial facilities, to the physical transport and processing of the ionized atoms that are the primary information carriers in quantum computing. The management of the traffic that takes place in these environments must be controlled for time- based efficiency, like throughput maximization and delay minimization, but also for more qualitative objectives like the preservation of the system liveness, i.e., the avoidance of potential deadlocks and the preservation of the ability of the system agents to complete successfully their running assignments. These qualitative problems can be rigorously addressed using models and analysis tools borrowed from theoretical computer science and the control- theoretic area of Discrete Event Systems. Their formal investigation also enables the formulation of an “optimal control” version of these problems through the notion of maximal permissiveness. In general, the deployment of maximally permissive liveness-enforcing supervision (LES) is a computationally hard task for most contemporary applications, due to the very large size of the involved state spaces. In this talk, we shall present a rather surprising result that establishes that for a very large and very practical class of the aforementioned transport systems, maximally permissive LES can be attained in time polynomial with respect to the size of the underlying guidepath network.

Spiridon (Spyros) Reveliotis

Georgia Institute of Technology
United States
November 17 | 13:00 UTC

PhD Students Forum


Talk 1

Opacity Enforcing Controller Synthesis for Stochastic Systems


Formal methods have become increasingly important issues for the design of complex engineering systems such as robots, autonomous vehicles and energy systems. Verification and synthesis of control strategies for temporal logics such as Linear Temporal Logic (LTL)  have attracted considerable attentions. However, information security and privacy issues have not been fully considered in the formal synthesis problem. Opacity is an information-flow property in the context of Discrete-Event Systems (DES), which is a very important security constraint in Cyber Physical Systems (CPS). In this talk, I will first introduce the notion of opacity and briefly present synthesis approaches for opacity using supervisory control theory in DES. Then I will focus on the problem of synthesizing optimal control policies for stochastic control systems to achieve LTL specifications under security constraints.

Yifan Xie

Shanghai Jiao Tong University
Talk 2

Applications of Supervisory Control to Secure System Design and Attack Synthesis


As systems have been evolving larger and more networked, it becomes increasingly crucial to take system security into account. Due to the proliferation of different system architectures and heterogenous networks, however, keeping systems secure and designing robust protocols against attacks can be significantly challenging. From the side of system administrators, one of their central responsibilities is for preventing secret information in the system from being unintentionally exposed. For example, sensitive information stored in the system such as phone numbers, credit card transactions, passwords, or privileges (e.g., root user in Linux), should not be available freely to external agents. Besides, it is important to minimize the associated cost of implementing protections, including a decrease of usability, while the system achieves a required security level. In this talk, I first introduce a DES-based approach to model this security problem and a methodology to find a protection policy that help administrators figure out which transitions in the system must be protected. From the side of attackers, on the other hand, insecure channels/networks can be typical targets for attackers. Such an attack scheme is called Person-In-The-Middle attack. Moreover, since networked systems tend to rely on standardized protocols, vulnerabilities or misuses of protocols can be a cause of serious security incidents. Considering that the attackers’ goal is to lead the system to a violation of required properties of protocols, I will present how to synthesize attack strategies so that the attacker always eventually wins, to examine whether attackers can exploit vulnerable communication protocols. This problem of attack synthesis can be solved by leveraging existing techniques of supervisory control, and that methodology will be demonstrated with one of the most common communication protocols today: Transmission Control Protocol (TCP), specifically the phase of connection establishment using three-way handshake.

Shoma Matsui

Queen's University

No event due to CDC 2022