HOMFLY-PT homology for general link diagrams and braidlike isotopy

Abstract

Khovanov and Rozansky's categorification of the HOMFLY-PT polynomial is invariant under braidlike isotopies for any link diagram and Markov moves for braid closures. To define HOMFLY-PT homology, they required a link to be presented as a braid closure, because they did not prove invariance under the other oriented Reidemeister moves. In this text we prove that the Reidemeister IIb move fails in HOMFLY-PT homology by using virtual crossing filtrations of the author and Rozansky. The decategorification of HOMFLY-PT homology for general link diagrams gives a deformed version of the HOMFLY-PT polynomial, $P^b(D)$, which can be used to detect nonbraidlike isotopies. Finally, we will use $P^b(D)$ to prove that HOMFLY-PT homology is not an invariant of virtual links, even when virtual links are presented as virtual braid closures.

26 pages, many TikZ figures