Oberseminar (WiSe 2024/25)

Das Oberseminar des Lehrstuhls für Theoretische Informatik findet dienstags 14:15-15:45 in Raum 00.131-128 (Cauerstraße 11) statt.

Das Oberseminar steht Masterstudierenden und Doktoranden sowie bei Interesse Bachelorstudierenden offen.
Die Themenwahl erfolgt nach Vereinbarung entsprechend den Schwerpunkten des Lehrstuhls.

Bei Nachfragen gerne per Mail an den Seminarleiter (Prof. Dr. Lutz Schröder), Anmeldung zur Mailingliste: TCS-Seminar Mailinglist

Vorträge

Current Talk
Tuesday, 19/11/2024	Conformance Games for Graded Semantics Jonas Forster Slides Abstract In concurrency theory, a range of different notions of equivalence can be characterized via Spoiler-Duplicator games; for example, most equivalences on the linear-time / branching-time spectrum come with such characterizations. In this talk, we build on work by Ford et al. that extends Spoiler-Duplicator type games to the coalgebraic setting via the framework of graded semantics. We generalize this approach to cover other types of process comparison beyond equivalence, such as behavioural preorders or pseudometrics. At first, we abstract notions of behavoiural conformance in terms of topological categories. We obtain a sound and complete generic game for behavioural conformances in this sense, for which we furthermore derive a syntactic perspective by instantiating to topological categories that can be presented in terms of relational structures.
Upcoming Talks
Tuesday, 26/11/2024	TBA Üsame Cengiz Abstract TBA
Tuesday, 03/12/2024	TBA Pouya Partow Abstract TBA
Tuesday, 10/12/2024	TBA Florian Guthmann Abstract TBA
Tuesday, 10/12/2024	TBA Moritz Blöcher Abstract TBA
Tuesday, 17/12/2024	TBA Simon Prucker Abstract TBA
Tuesday, 07/01/2025	TBA Florian Frank Abstract TBA
Tuesday, 14/01/2025	TBA Robin Jourde Abstract TBA
Tuesday, 21/01/2025	TBA Max Ole Elliger Abstract TBA
Tuesday, 21/01/2025	TBA Philip Kaluđerčić Abstract TBA
Tuesday, 28/01/2025	TBA Stefan Gebhart Abstract TBA
Tuesday, 04/02/2025	TBA Merlin Humml Abstract TBA
Previous Talks
Tuesday, 12/11/2024	The λμμ̃-Calculus as a Setting for (Formalist) Argumentation Max Rapp Slides Abstract In this work-in-progress talk, we will take a Curry-Howard correspondence inspired perspective on formal argumentation theory. To this end, a dialectical variant of the (terribly named) calculus (sometimes “Matilda”) is presented and used to study central argumentation-theoretic concepts such as argument, attack (rebuttal and undercut), support, defaults and burden of proof. We will discuss some examples using an extension of the Fellowship prover for the λμμ̃-Calculus and explore possible directions for future work (rewriting, categorical semantics).
Tuesday, 05/11/2024	Behavioural Metrics for Higher-Order Coalgebras Henning Urbat Slides Abstract Higher-order coalgebras are a convenient abstract setting for modelling higher-order languages and their operational semantics. In this talk, I introduce a fibrational approach to reasoning about congruence properties of higher-order coalgebras. It uniformly applies to various notions of applicative bisimilarity and applicative distances known in the literature, as well as to new settings such as higher-order languages combining nondeterministic and probabilistic effects.
Tuesday, 29/10/2024	Algebraic Language Theory with Effects Fabian Lenke Slides Abstract Regular languages – the languages accepted by deterministic finite automata – are known to be precisely the languages recognized by finite monoids. This characterization is the origin of algebraic language theory. In the present paper, we generalize this result to automata with computational effects given by a monad, thereby providing the foundations of an effectful algebraic language theory. Our prime application is a novel algebraic approach to languages computed by T-FA, which are finite automata with effects given by a monad T. We show that these languages coincide with languages recognized by finite monoids via effectful monoid morphisms, and languages recognized by T-bimonoids, and moreover T-monoids if the monad T is commutative. In this framework, we derive novel characterizations are for languages computed probabilistic finite automata, nondeterministic probabilistic finite automata, and weighted finite automata over arbitrary semirings.
Tuesday, 27/08/2024	Towards Generalizing Probability Monads Nico Wittrock Slides Abstract This 45-minutes-talk will cover some probability monads, and generalizations. In the first section, we will encounter some classical probability monads. This will lead us to weakened products and the framework of Markov categories. As a short demonstration of this formalism, we will consider (a categorical version of) de Finetti’s theorem. The second part then addresses generalizations: imprecise probabilities, such as Dempster-Shafer-belief functions, model situations with insufficient knowledge. Do they fit into the framework of Markov categories? Do they even have probability monads? This is still an open question. Non-commutative probability is another way of generalization; I will shortly show how this is formulated in terms of C*-algebras, and point to recent results on involutive / quantum Markov categories.

Vorträge

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