SEMINARIUM

TEORIA DWOISTOŚCI

KATEDRY METOD MATEMATYCZNYCH FIZYKI



W dniu 16. marca 2017 r. o godzinie 10:15

Józef H. Przytycki (The George Washington University)

wygłosi wykład pt.

"Torsion in Khovanov homology"

Streszczenie
We recall the definition of the Khovanov homology of links and mention its modification to odd Khovanov homology. We discuss the fact that in Khovanov homology of links, presence of ℤ2-torsion is a very common phenomenon. We outline the several reasons for this observation (e.g., Hochschild homology of the algebra ℤ[x]/(x2), crucial in Khovanov homology, has only ℤ2 torsion). For other than ℤ2 torsion only a finite number of examples of knots with ℤn-torsion were known, none for n>8. In this talk, we show that there are infinite families of links whose Khovanov homology contains ℤn-torsion for 2 < n < 9 and ℤ2s-torsion for s < 24. We also introduce 4-braid links with ℤ3-torsion which are counterexamples to the PS braid conjecture. We mention that our construction also provides an infinite family of knots with ℤ5-torsion in reduced Khovanov homology and ℤ3-torsion in odd Khovanov homology. Most of our examples are twisted torus knots and links.

Seminarium odbywa się w czwartki w godzinach 10:15–12:00 w sali 2.23 w głównym budynku Wydziału Fizyki UW przy ul. Pasteura 5 (II p.) w Warszawie.
Dodatkowe informacje są zamieszczane na stronie http://oldwww.fuw.edu.pl/KMMF/sem.czw.przedp.html.