[K-OS] Knot Online Seminar
[K-OS] is an online research seminar which focuses on knot theory and low-dimensional topology. It happens every Thursdays from 14:00 to 15:00 (
CET/CEST Berlin, Brussels, Madrid, Paris, Rome, Vienna, Warsaw, Zurich) on
Zoom.
It is organized by Louis-Hadrien
Robert and Emmanuel
Wagner. It benefits from logistical support from the
CNRS and the university of
Geneva.
25/02/2021 NO SEMINAR.
04/03/2021
- Speaker: Daniel Ruberman (Brandeis University).
- Title: A Levine–Tristram invariant for knotted tori.
- Abstract: In 1969, Tristram and Levine independently
introduced an integer-valued function of a knot, depending
on the choice of a unit complex number. It gives rise to a
concordance invariant that in turn shows that the the
concordance group is infinitely generated. I will explain
a generalization of this invariant to the setting where
the 3-sphere is replaced by X, a homology
𝕊1×𝕊3, and the
knot is replaced by an embedded torus (that carries the
first homology). I will show how to compute this
invariant, and discuss its relation to recent work of
Echeverria that counts SU(2) connections on the
complement of the torus with specified holonomy on the
meridian.
11/03/2021
- Speaker: Akram Alishahi (University of Georgia).
- Title: TBA.
- Abstract: TBA.
18/03/2021
- Speaker: Ricard Riba Garcia (Universitat Autònoma de Barcelona).
- Title: TBA.
- Abstract: TBA.
25/03/2021
01/04/2021
- Speaker: Maciej Borodzik (Uniwersytet Warszawski).
- Title: Non-rational, non-cuspidal plane curves
via Heegaard Floer homology.
- Abstract: Let C be a complex curve in
ℂℙ2. Using d-invariants from
Heegaard Floer theory we provide topological constraints
for possible singularities of C. The novelty is
that we do not need to assume that C is rational,
or that all its singularities have one branch, so we
generalize previous results of Bodnar, Borodzik,
Celoria, Golla, Hedden and Livingston. As an
application, we show precise examples of surfaces in
ℂℙ2, for which "genus cannot be
traded for double points". This is a joint project with
Beibei Liu and Ian Zemke.
08/04/2021
- Speaker: Andrew Lobb (Durham University).
- Title: Four-sided pegs fitting round holes fit all smooth holes.
- Abstract: Given a smooth Jordan curve and a cyclic
quadrilateral (a cyclic quadrilateral is a quadrilateral
that can be inscribed in a circle) we show that there
exist four points on the Jordan curve forming the vertices
of a quadrilateral similar to the one given. The
smoothness condition cannot be dropped (since not all
cyclic quadrilaterals can be inscribed in all
triangles). The proof involves some results in symplectic
topology. No prior knowledge assumed. Joint work with Josh
Greene.
15/04/2021, 22/04/2021NO SEMINAR.
29/04/2021
- Speaker: David Leturcq (Research Institute for Mathematical Sciences, Kyōto University).
- Title: TBA.
- Abstract: TBA.
06/05/2021
- Speaker: Jacob Rasmussen (University of Cambridge)
- Title: TBA.
- Abstract: TBA.
13/05/2021
20/05/2021
27/05/2021
- Speaker: Raphael Zentner (Universität Regensburg)
- Title: TBA.
- Abstract: TBA.
17/06/2021
- Speaker: Vincent Colin (Université de Nantes)
- Title: TBA.
- Abstract: TBA.
24/06/2021