[K-OS] Knot Online Seminar
[K-OS] is an online research seminar which focuses on knot
theory and low-dimensional topology. Talks will be delivered
by authors of recent arXiv articles of significant interest.
It happens the 3rd Thursday of every month
from 16:15 to 17:15
(
CET/CEST Berlin,
Brussels, Madrid, Paris, Rome, Vienna, Warsaw, Zurich)
on
Zoom.
Current time:
It is organized by
Marc
Kegel,
Alexandra
Kjuchukova,
Lukas
Lewark,
Delphine
Moussard
and
Anne-Laure
Thiel.
It benefits from logistical support from
the
CNRS and
ETHZ.
If there is a recent arXiv preprint which you would like to see featured on the seminar, please email the organizers with your suggestion.
The K-OS talks are also listed in a
Google Calendar.
Forthcoming Talks
19 November 2026
- Speaker: Filippo Baroni (Trinity College Dublin)
- Certifying fibredness and hyperbolicity of 3-manifolds (arXiv:2606.23284)
- Abstract: In this talk, we discuss the computational complexity of the following problems: given a 3-manifold, does it fibre over the circle? And if it does, is it hyperbolic? We show that the problem of deciding fibredness of a 3-manifold lies in NP – meaning that a positive answer can be certified "efficiently"; this provides a slight generalisation of a theorem of Saul Schleimer. We also describe how hyperbolicity of a fibred 3-manifold can be certified "efficiently", although not quite enough to show that this problem lies in NP. By combining these results with a recently announced theorem of Marc Lackenby, we conclude that the problem of deciding if a knot in the 3-sphere is hyperbolic lies in NP.
17 December 2026
