Computational Logic Seminar

General Information

This is the website of the research seminar of the Computational Logic Group at the Institute of Discrete Mathematics and Geometry of TU Wien. The seminar usually takes places on Wednesdays from 10:00 to 11:00 in the Zeichensaal 1, 8th floor, green area. The seminar is organised by J. Aguilera, E. Fokina and S. Hetzl.

If you want to receive talk announcements by e-mail, please subscribe to the mailing list of this seminar on its administration page.

April 15, 2026: Noam Greenberg (Victoria University of Wellington)
title: Forcing, untagging, and graph colourings
abstract:
I will present a family of notions of forcing that are useful in showing that certain graphs don’t have countable colourings in particular Borel classes. This is joint work with Lecomte, Turetsky and Zeleny. This kind of forcing was also used in work with J. Miller, Soskova, and Turetsky to find the Borel rank of classes of Turing degrees defined by iterating the Turing jump.

April 22, 2026: Andrea Volpi (University of Warsaw)
title: The strength of Ramsey's theorem for $\a$-large sets
abstract:
We present joint work with Lorenzo Carlucci and Konrad Zdanowski on Ramsey-like principles $\RT^{!\alpha}_k$, extending Ramsey's theorem to colorings of exactly $\alpha$-large finite subsets of $\mathbb{N}$ in the sense of Ketonen and Solovay. For each countable $\alpha < \Gamma_0$ and $k \geq 2$, we show over $\RCA_0$ that these principles form a hierarchy matching closure under transfinite iterations of the Turing jump along $\alpha$, yielding a fine-grained classification between $\ACA_0$ and $\ATR_0$.