This is the homepage of the ESSLLI 2026 workshop whose aim is to bring together researchers who apply semantic approaches in the study of expressiveness and complexity problems in logic. In particular, the objective is to provide a platform for researchers who apply tools from
- category theory,
- algebra, and
- topology
in the algorithm-oriented fields of theoretical computer science, such as
- automata theory,
- descriptive complexity,
- finite model theory, and
- constraint satisfaction.
Examples include the use of category theory in automata theory, formal language theory, in the study of graph invariants, and dynamic programming algorithms. Similarly relevant are applications of algebra and topology in CSP, or applications of duality theory and topology in finite model theory and quantum isomorphisms.
Dates
- Workshop dates: 10-14 August 2026, in Prague
- Submission: 30 April 2026
- Notification: 15 May 2026
- ESSLLI Registration: early until May 31, late after June 1
Invited Lectures
- Samson Abramsky (on game comonad)
- Jakub Opršal (on the algebraic approach to CSP)
- Jiří Adámek (on universal coalgebra)
Contributed Talks
- Gabriel Goren - TBA
- Tomas Jakl - TBA
- Damiano Mazza - A Categorical Approach to Descriptive Complexity
- Paul-Andre Mellies - TBA
- Larry Moss - TBA
- Cihan Okay - Double categories for adaptive quantum computation
- Luca Reggio - TBA
- Nihil Shah - TBA
- Masaya Taniguchi - Decidability of Derivability under Depth Constraints in CG with B and T
- Henning Urbat - Demystifying Codensity Monads via Duality
- Haitian Wang - A Categorical Perspective on Kripke Models and Dynamic Epistemic Logic
Submitting instructions
Apart from invited lectures there will be a number of contributed talks. If you are interested in giving a talk, please write to tomas.jakl@cvut.cz with a title of your talk and a short abstract (1-2 paragraphs).
Although the deadline for submission is 30 April 2026, please feel free to write earlier, to express the intent to submit.
Schedule overview
| Monday | Tuesday | Wednesday | Thursday | Friday | |
|---|---|---|---|---|---|
| Session 1 (11:00-12:30) | Introductory Lecture | Introductory Lecture | Introductory Lecture | 2 talks | 2 talks |
| Session 2 (14:00-15:30) | 2 talks | 2 talks | Problem Session | 2 talks | Problem Session |
| Evening | Workshop Dinner |
Moreover, the participants are encouraged to also take part in the rest of the (Week 2) ESSLLI programme.
Local information
Please follow the instructions at the ESSLLI website.
We would only add the following:
- Please book your hotels early. Summer is a busy tourist season and the most affordable hotels run out quickly.
- Public transport is the best way to get around Prague. You can use your contactless card to buy tickets right on the buses and trams. In case you also travel by subway, these have to be purchased before entering the subway. There should be ticket machines at the entrance. Also, you can transfer between different modes of transport on a single ticket, so long as this is within the ticket’s time constraints (30 min, 90 min, 24 hours).
- In case you really need to use taxi, it is recommended to use Uber or similar apps as the standard taxi drivers do not have a good reputation when it comes to treating tourists.
Similar events
Since 2020, the community around the algebraic approach to CSP has met yearly at the so-called CSP World Congress. The categorical approach to automata theory and formal languages concentrates around the Conference on Algebra and Coalgebra in Computer Science (CALCO), held every odd year since 2005, and the Workshop on Coalgebraic Methods in Computer Science (CMCS), held every even year. Also, in 2025, there was a Dagstuhl workshop called Categories for Automata and Language Theory aimed at the same community.
However, our scope is wider than these events. It follows the tradition of the one- and two-day Structure meets Power series of workshops, see 2026, 2024, 2023, 2022, 2021. Unlike with the Structure meets Power workshop, which are typically short, this workshop is a dedicated multi-day workshop designed to provide more space for interaction.
Organisers
- Tomáš Jakl, Czech Technical University
- Dan Marsden, University of Nottingham
Acknowledgement
The workshop is funded by the EU’s Horizon Europe research and innovation programme under the Marie Skłodowska-Curie grant agreement No 101111373. 