Oberseminar SoSe 2026

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. Die Vortragstermine werden am ersten Termin in der Vorlesungszeit festgelegt.

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

Vorträge

  


Current Talks


Tuesday, 28.04.2026


The Substitution Tensor in Presheaves and Nominal Sets
Fabian Lenke
Abstract
Presheaves and nominal sets provide alternative abstract models of sets of syntactic objects with free and bound variables, such as λ-terms. One distinguishing feature of the presheaf-based perspective is its elegant syntax-free characterization of substitution using a closed monoidal structure. In this talk, we introduce a corresponding closed monoidal structure on nominal sets, in the spirit of Fiore et al.'s substitution tensor for presheaves over finite sets. To this end, we present a general method to derive a closed monoidal structure on a category from a given action on that category. We demonstrate that this method not only uniformly recovers known substitution tensors for various kinds of presheaf categories but also yields novel notions of substitution tensor for nominal sets and their relatives, such as renaming sets. In doing so, we shed new light on different incarnations of nominal sets and (pre-)sheaf categories and establish a number of novel correspondences between them.




Upcoming Talks


Tuesday, 05.05.2026


TBA
Simon Prucker
Abstract
TBA




Tuesday, 12.05.2026


TBA
Prof. Dr. Cathérine Meusburger (Department Mathematik, Lie-Gruppen und Darstellungstheorie)
Abstract
TBA




Tuesday, 19.05.2026


TBA
Stefan Gebhart
Abstract
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Tuesday, 19.05.2026


TBA
Üsame Cengiz
Abstract
TBA




Tuesday, 26.05.2026


Sitzung fällt wegen Bergdienstag aus



Tuesday, 02.06.2026


TBA
Jiří Adámek (TU Braunschweig)
Abstract
TBA




Tuesday, 09.06.2026


TBA
Felix Lützow
Abstract
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Tuesday, 09.06.2026


TBA
Jakob Roßkopf
Abstract
TBA




Tuesday, 16.06.2026


TBA
Jonas Forster
Abstract
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Tuesday, 23.06.2026


TBA
Ole Elliger
Abstract
TBA




Tuesday, 30.06.2026


TBA
Florian Guthmann
Abstract
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Tuesday, 07.07.2026


TBA
N.N.
Abstract
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Tuesday, 14.07.2026


TBA
Maximilian Rumi
Abstract
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Tuesday, 14.07.2026


TBA
Henning Urbat
Abstract
TBA




Previous Talks


Tuesday, 21.04.2026


Finch: A Browser-Based Proof Assistant for Fitch-Style Natural Deduction
Leon Vatthauer
SlidesAbstract
Finch is a browser-based proof assistant designed to help students construct correct Fitch-style natural deduction proofs by providing helpful error messages and an intuitive interface.
The application was developed for my Master's project and is written purely in Haskell using the Miso library together with GHC's WebAssembly backend. In this talk I will showcase Finch, explain how the proof checker operates, and provide a brief introduction to web development in Haskell.

Current Talks
Tuesday, 28.04.2026	The Substitution Tensor in Presheaves and Nominal Sets Fabian Lenke Abstract Presheaves and nominal sets provide alternative abstract models of sets of syntactic objects with free and bound variables, such as λ-terms. One distinguishing feature of the presheaf-based perspective is its elegant syntax-free characterization of substitution using a closed monoidal structure. In this talk, we introduce a corresponding closed monoidal structure on nominal sets, in the spirit of Fiore et al.'s substitution tensor for presheaves over finite sets. To this end, we present a general method to derive a closed monoidal structure on a category from a given action on that category. We demonstrate that this method not only uniformly recovers known substitution tensors for various kinds of presheaf categories but also yields novel notions of substitution tensor for nominal sets and their relatives, such as renaming sets. In doing so, we shed new light on different incarnations of nominal sets and (pre-)sheaf categories and establish a number of novel correspondences between them.
Upcoming Talks
Tuesday, 05.05.2026	TBA Simon Prucker Abstract TBA
Tuesday, 12.05.2026	TBA Prof. Dr. Cathérine Meusburger (Department Mathematik, Lie-Gruppen und Darstellungstheorie) Abstract TBA
Tuesday, 19.05.2026	TBA Stefan Gebhart Abstract TBA
Tuesday, 19.05.2026	TBA Üsame Cengiz Abstract TBA
Tuesday, 26.05.2026	Sitzung fällt wegen Bergdienstag aus
Tuesday, 02.06.2026	TBA Jiří Adámek (TU Braunschweig) Abstract TBA
Tuesday, 09.06.2026	TBA Felix Lützow Abstract TBA
Tuesday, 09.06.2026	TBA Jakob Roßkopf Abstract TBA
Tuesday, 16.06.2026	TBA Jonas Forster Abstract TBA
Tuesday, 23.06.2026	TBA Ole Elliger Abstract TBA
Tuesday, 30.06.2026	TBA Florian Guthmann Abstract TBA
Tuesday, 07.07.2026	TBA N.N. Abstract TBA
Tuesday, 14.07.2026	TBA Maximilian Rumi Abstract TBA
Tuesday, 14.07.2026	TBA Henning Urbat Abstract TBA
Previous Talks
Tuesday, 21.04.2026	Finch: A Browser-Based Proof Assistant for Fitch-Style Natural Deduction Leon Vatthauer Slides Abstract Finch is a browser-based proof assistant designed to help students construct correct Fitch-style natural deduction proofs by providing helpful error messages and an intuitive interface. The application was developed for my Master's project and is written purely in Haskell using the Miso library together with GHC's WebAssembly backend. In this talk I will showcase Finch, explain how the proof checker operates, and provide a brief introduction to web development in Haskell.

Vorträge

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