[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.
It is organized by
Alexandra
Kjuchukova,
Lukas
Lewark,
Delphine
Moussard
and
Emmanuel
Wagner.
It benefits from logistical support from
the
CNRS, the university
of
Paris and the
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
26 March 2026
- Speaker: José Andrés Rodríguez Migueles (CIMAT)
- On the existence of universal links in three-manifolds (arXiv:2511.14985)
- Abstract: We will discuss the existence of branched coverings between closed 3-manifolds, with emphasis on universal knots and links. I will prove that the only closed 3-manifolds that admit a universal link are spherical. Furthermore, we distinguish between universal links and complement universal links and show that these notions do not coincide in general, by exhibiting infinitely many examples of complement universal links that are not universal. Also, we prove that there is no closed aspherical 3-manifold, such that every closed, aspherical 3-manifold is a branched covering over it. Finally, we characterize the closed 3-manifolds admitting branching coverings from P3#P3, and deduce that there is no closed reducible 3-manifold, such that every closed reducible 3-manifold is a branched covering over it. This a work in colaboration with Araceli Guzmán, Jesús Rodríguez and Francisco González-Acuña.
16 April 2026
- Speaker: Keegan Boyle (New Mexico State University)
- Involutions on the 4-sphere (arXiv:2512.22724)
- Abstract: On topological manifolds, it is natural to study symmetries which have some regularity condition near the fixed points, and in this talk I will assume the existence of an equivariant tubular neighborhood of the fixed-point set; we call such involutions fixed-point linear. Our main theorem is that all fixed-point linear involutions on S4 with a 1-dimensional fixed-point set are conjugate in the homeomorphism group, and I will explain how this theorem completes the classification of fixed-point linear involutions on S4. Along the way, we will see that equivariant tubular neighborhoods need not be unique, in contrast with the non-equivariant setting. The proof uses modified surgery theory and an equivariant version of the generalized Schoenflies theorem. Time permitting, I will also discuss an application to equivariant (topological) concordance of strongly negative amphichiral knots. This is joint work with Wenzhao Chen and Anthony Conway.
