Workshop accompanying the PhD defence of Ruben Turkenburg

The workshop will be held in the afternoon on Thursday 18th June 2026.

Venue

Huygensgebouw, Room HG00.086
Heyendaalseweg 135
6525AJ Nijmegen
Website

Program (provisional)

14:30 – 15:00	Ana Sokolova
15:00 – 15:30	Break
15:30 – 16:00	Henning Basold Title: Coalgebraic Causality - Notions and Extensions Abstract Causality arises naturally as a restriction of morphsims between final coalgebras. In this talk, I will present different ways of defining causality and how it can be extended to a wider class of morphisms that is still well-behaved. In particular, causality corresponds to non-expansive maps, while the extension will capture uniform continuity. This is based on joint work with Tanjona Ralaivaosaona and Jurriaan Rot.
16:00 – 16:30	Lutz Schröder Title: Nominal Automata with Name Deallocation Abstract Data words with binders formalize concurrently allocated memory. Most name-binding mechanisms in formal languages, such as the lambda-calculus, adhere to properly nested scoping. In contrast, stateful programming languages with explicit memory allocation and deallocation, such as C, commonly interleave the scopes of allocated memory regions. This phenomenon is captured in dedicated formalisms such as dynamic sequences and bracket algebra, which similarly feature explicit allocation and deallocation of letters. One of the classical formalisms for data languages are register automata, which have been shown to be equivalent to automata models over nominal sets. In the present work, we introduce a nominal automaton model for languages of data words with explicit allocation and deallocation that strongly resemble dynamic sequences, extending existing nominal automata models by adding deallocating transitions. Using a finite NFA-type representation of the model, we establish a Kleene theorem that shows equivalence with a natural expression language. Moreover, we show that our non-deterministic model allows for determinization, a quite unusual phenomenon in the realm of nominal and register automata.