Seminar
Logic Seminar
The Logic seminar is held on Wednesdays, usually at 12-14. If not separately specified, the talks always start at a quarter past.
We occasionally have online talks - the permanent Zoom room for the seminar is: https://helsinki.zoom.us/j/62891400777?pwd=UldCeThTaTJVQjUzUFo4S2ErcndNQT09 (Meeting ID: 628 9140 0777, Passcode: 164195)
The seminar is led by prof. Juha Kontinen and Åsa Hirvonen.
Schedule of the spring term 2026
Wed 14.1.2026 12-14, C124
No seminar
Wed 21.1.2026 12-14, C124
Kai Sauerwald: New Results on the Complexity of Preferential Reasoning
Abstract: In this talk, we will consider recent results on the complexity of preferential reasoning in the style of Kraus, Lehmann, and Magidor. We begin with a brief overview of the approach and classical results. Novel complexity results on propositional preferential reasoning are presented. In the last part, we will then consider the combination of preferential reasoning with propositional dependence logic and the (non)feasibility of inference with this context.
Wed 28.1.2026 12-14, C124
Veeti Ahvonen (Tampere University): Logical Foundations for Modern Computational Models
Wed 4.2.2026 12-14, C124
seminar cancelled
Wed 11.2.2026 12-14, C124
Octavian Neculau: A non-structure theorem for the theory of differentially closed fields
Abstract: One of the most common ideas in all areas of mathematics is to have a way of telling whether two, or more considered objects are independent in a suitable sense. It turns out that that non-forking provides us a way of talking about independence in model theory.
In this talk I will try to give an overview of my master's thesis, focusing on the connection between algebra and model theory, in particular on how non-forking relates to independence notions we usually define for a particular class of algebraic structures. The main result of my thesis, which will be briefly presented, states that for all regular cardinals $\kappa > \omega_1$ such that $\kappa^\omega = \kappa$, the theory of differentially closed fields has $2^\kappa$-many non-isomorphic models of cardinality $\kappa$, unlike the theory of algebraically closed fields.
Wed 18.2.2026 12-14, C124
Matilda Häggblom: Intersections in team semantics and an axiomatization of propositional inclusion-dependence logic
Abstract: We examine intersection closure in team semantics and define a logic expressively complete for all intersection-closed team properties. A novel variant of the disjunction is introduced for this purpose, and we compare it to the split-disjunction. This comparison shows that the full team in the intersection‑closed setting serves a role analogous to that of the empty team in the union‑closed setting.
We also axiomatize propositional inclusion logic extended with dependence atoms, based on joint work with Fan Yang. The axiomatization takes on a surprisingly modular form and provides us with a method that, under certain conditions, can be used for other logics augmented with dependence atoms.
Wed 25.2.2026 12-14, C124
No seminar
Wed 4.3.2026 12-14, C124
Exam week, no seminar
Wed 11.3.2026 12-14, C124
Andrew Cropper: TBA
Wed 18.3.2026 12-14, C124
Manon Blanc (TBA)
Wed 25.3.2026 12-14, C124
Ur Ya'ar (TBA)
Wed 1.4.2026 12-14, C124
Teymur Ismikhanov (TBA)
Wed 8.4.2026 12-14, C124
Wed 15.4.2026 12-14, C124
Phokion Kolaitis: TBA
Wed 22.4.2026 12-14, C124
Instead of the seminar there is a Workshop on Team Semantics in the city centre 20.-22.4.
Wed 29.4.2026 12-14, C124
Jarkko Kari: TBA
Wed 6.5.2026 12-14, C124
Exam week, no seminar