Advanced Concurrency Theory

Advanced Concurrency Theory Seminar

Audience

This Seminar addresses Master and Bachelor students in Computer Science and related study programs that mandate participation in at least one Seminar.

The first meeting

The first meeting takes place on Tuesday, October 25, starting 08:15 in room 528 of E1 3.

Structure

• casting - November 15: 5 minutes presentation on timed automata. For papers to start from, see under Materials in the system (you will only present without any audience, you are not admitted to listen to the talks of the others; we will ask the author of the presentation that we consider best to redo the presentation on November 22.)
  10% of the final grade
• CCS, CSP and all that - November 22:  a crisp introduction to variations of process calculi brought to you by Prof. Hermanns. In addition, there will be a presentation of the best presentation on TA selected earlier. 
  0% of the final grade, but participation mandatory
• presentations - end November to early February: 45 minutes presentations, one or two presentations per week,
  you probably cannot present all the material in these 45 minutes - you need to construct a good story out of the material
  31% of the final grade
• writeup - draft until February 14 (23:59), final version until March 31 (23:59): writeup of your presentation in a book chapter style.
  like in your presentation, you need to construct a good story and explain it properly therein (examples, exercises, etc.)
  29% of the final grade
• reviews - until March 7 (23:59): you will be assigned two write-ups of your colleagues, you need to read them and give a thorough written feedback
  10% of the final grade 
• active participation: this involves feedback to the presentations of your colleagues and, most importantly, participation in the "scientific" discussions during and after the presentations
  20% of the final grade

Overview of the seminar

This Seminar has two goals:

1. to practice and to refine the skills of "scientific presentation", "scientific argumentation", and "scientific reflection";
2. to learn more about various theoretically challenging and practically relevant concurrency models.

Despite its importance and more than three decades of highly active research, concurrent systems are still less understood than sequential systems. A comprehensive model of concurrency, comparable to Turing machines and the lambda calculus for sequential programs, is yet to be established for concurrency. In our seminar we will study some of the most important models and results for concurrency, and we will see why concurrency is so difficult to understand.

The goal of the seminar is to provide a broad overview of the theoretical underpinnings of concurrency theory. For example, we will discuss popular process algebras such as CCS, the pi calculus and mobile ambients. Further topics include input/output automata, modal transition systems and Petri nets as well as models of true (i.e. non-interleaving) concurrency.  In addition we will look at various concurrent automata models which in different senses extend finite automata. Every such extension is motivated by a concrete practical application area. This way, we can reason about timed behaviour of real-time systems; describe behaviour of reactive systems using languages composed not of finite but of infinite words; specify classes of models using a modal automata; or reason about randomness using probabilistic automata. We will see how these modelling feature are crucial for the respective application areas.

We selected a number of papers for each of these areas. Participation in the seminar includes writing a paper  to give some motivation, examples, links to relevant literature and to provide the theoretical background of the selected topic. Furthermore, each participant gives a formal presentation (approx. 45 minutes) to explain the topic to the audience.

List of papers (incomplete)

1. Process Algebra (in the true sense)

   M. Hennessy, R. Milner: Algebraic Laws for Nondeterminism and Concurrency

   R. Milner: A complete axiomatisation for observational congruence of finite-state behaviours

2. Bisimulation minimization

   J. C. Fernandez. An implementation of an efficient algorithm for bisimulation equivalence

3. Event-structures (and non-interleaving semantics of CCS)

   H. Bowman, R. Gomez: Calculi and Automata for Modelling Untimed and Timed Concurrent Systems (Chapter 4).

4. Petri Nets

   E.R. Olderog: Nets, Terms and Formulas

   (focus on chapter 3 and 2)

5. Model based testing

   R. De Nicola, M. Hennessy:Testing Equivalences for Processes

   J. Tretmans. Model Based Testing with Labelled Transition Systems

6. Value-passing semantics

   M. Hennessy, H. Lin: Symbolic Bisimulations.

7. Spectral Analysis

   R. J. van Glabbeek: The Linear Time - Branching Time Spectrum I

   (select from the long version from the Handbook of Process Algebra. For the bravehearts, there is a Spectrum II)

8. Interface Automata

   L. de Alfaro, T. A. Henzinger: Interface Automata

   (for further context, see also: L. de Alfaro: Game Models for Open Systems)

9. Probabilistic automata and PCCS

   M. Stoelinga: An introduction to probabilistic automata. Bulletin of the European Association for Theoretical Computer Science, 2002

   C. Baier: On algorithmic verification methods for probabilistic systems (chapter 4)

10. Probabilistic timed automata

    A. Hartmanns: On the analysis of Stochastic Timed Systems (chapter 5)

    Marta Z. Kwiatkowska, Gethin Norman, Roberto Segala, and Jeremy Sproston. Automatic verification of real-time systems with discrete probability distributions.

11. Stochastic automata

    J.-P. Katoen, P. R. D'Argenio: General Distributions in Process Algebra.

12. Markov automata

    C. Eisentraut, H. Hermanns, L. Zhang: Concurrency and Composition in a Stochastic World.

    C. Eisentraut, H. Hermanns, L. Zhang: On Probabilistic Automata in Continuous Time.

13. Priced and energy timed automata

    an overview of priced TA models: P. Bouyer, U. Fahrenberg, K. G. Larsen, N. Markey. Quantitative analysis of real-time systems using priced timed automata

    more technical content for energy TA: P. Bouyer, K. G. Larsen, N. Markey. Lower-Bound Constrained Runs in Weighted Timed Automata

    (it also possible to present only the overview, and search for some technical parts in research papers cited in the overview)

14. Hybrid automata

    R. Alur, C. Courcoubetis, N. Halbwachs, T.A. Henzinger, P.-H. Hod, X. Nicollin, A. Olivero, J. Sifakis, S. Yovine: The algorithmic analysis of hybrid systems