The workshop is expected to bring together around 20 researchers to work on topics connected closely to the Černý Conjecture. Rather than just giving a forum for exchanging recent results, the ABCDays are designed to work out promising research tasks or even projects and to install cooperations.

The program will consist of four invited talks and free discussions on specific problems proposed by participants. The participants are invited to prepare short talks (15-20 minutes) on an unsolved problem or research suggestions in the area close to the Černý Conjecture. These talks will be organized in Problem Sesions and should be aimed at provoking discussion. The time for comments and questions will be in principle unlimited.

The workshop will be held at the Institute of Mathematics of the University of Wrocław. The scientific program will start on Monday, June 23, 10 a.m., and will end on Wenesday, June 25, 1 p.m. Here you find the detailed schedule .

Invited Talks

Two invited talks concern the recent solution of the Road Coloring Problem .

The third ivited talk presents a sort of iterated periodicity result in semigroups.

The author of the conjecture himself will talk about the connectioncs of the automata theory with applications.


In accordance with ABCD rules, participants from ESF countries are going to be reimbursed for meeting expenses: travel, accommodation, and meals. To make use of this opportunity one needs to register by writing an e-mail to one of the organizers containing the name, institution, postal address, e-mail address, and the statement whether he or she wishes or not to have a short-talk in Problem Sessions. In the former case please give a title and a few sentences describing the talk (in order to place it suitably in the plan of the workshop).

List of registered participants

  1. Jorge Almeida, Porto, Portugal
  2. Flavio D'Alessandro, Roma, Italy
  3. Tomasz Brengos, Warszawa, Poland
  4. Arturo Carpi, Perugia, Italy
  5. Jan Černý, Czech Republic
  6. Alessandra Cherubini, Milano, Italy
  7. Jan Florek, Wrocław, Poland
  8. Wit Foryś, Kraków, Poland
  9. Paweł Gawrychowski, Wrocław, Poland
  10. Mariusz Grech, Wrocław, Poland
  11. Aleksander Ivanov, Wrocław, Poland
  12. Bartosz Jabłoński, Warszawa, Poland
  13. Artur Jeż, Wrocław, Poland
  14. Łukasz Jeż, Wrocław, Poland
  15. Alica Kelemenová, Opava, Czech Republic
  16. Andrzej Kisielewicz, Wrocław, Poland
  17. Bernadette Mayrhauser, Linz, Austria
  18. Anna Mućka, Warszawa, Poland
  19. Christian Neumaier, Linz, Austria
  20. Claudia Nuccio, Milano, Italy
  21. Brunetto Piochi, Firenze, Italy
  22. Emanuele Rodaro, Milano, Italy
  23. Adam Roman, Kraków, Poland
  24. Wojtek Samotij, Wrocław, Poland/USA
  25. Avraham Trahtman, Ramat-Gan, Israel
  26. Mikhail Volkov, Ekaterinburg, Russia


The meals (in part) and accommodation are provided by the organizer. Refunds of travel costs will be made after the workshop strictly according to ESF financial rules for the reimbursement of expenses. These rules may be found on ESF pages in Guidelines for Proposers and Organizers of Science Meetings within a Programme.

In particular, ESF rules ask to travel at possibly modest costs (generally, these costs cannot exceed 500 Euros). These costs are reimbursed after the workshop on the basis of the original ticket (or equivalent original document) sent to the organizers in Wroclaw. (So you need to take care about keeping the tickets).


A main accommodation for participants will be provided by the organizers in the Tumski Hotel, which is located in the center of Wrocław on the Tumski Island, the oldest part of the city. We note that a regular reservation is for 3 nights for the period June 22-25. Those who for any reason would like to extend this reservation should contact the organizers.

Here you find directions on how to get to the Tumski Hotel and to the Institute of Mathematics.


Any questions concerning the workshop may be directed to:


The organizers: Alessandra Cherubini,  Andrzej Kisielewicz,  Avraham Trahtman.