# An introduction to Khovanov homology, Heegaard-Floer homology

I am interested in knot theory and low dimensional topology. I would like to start studying Khovanov homology and Heegaard-Floer homology.

I (partially) read the original paper of Khovanov and then watched an online lecture on Khovanov homology. I noticed that the lecture deals Khovanov homology more categorically. I think after the original work of Khovanov, people refined and generalized the definition or method of Khovanov homology.

So I would like to know how people deal Khovanov homology recently. Is there a standard textbook for graduate student on Khovanov homology?

(Also, I would like to learn Heegaar-Floer homology too. So if there is a standard text book fot this, please let me know.)

## 3 Answers

I highly recommend that you begin reading about Khovanov knot homology from the works of Dror Bar Natan.

In particular,

His exposition is clean, intuitive, and motivated by the geometric/cobordism perspective. I dare say it's fun to read.

Regarding, Heegaard-Floer Knot Homology, I'd go to the source: Ozsváth and Szabó.

• Dror Bar-Natan also posts almost all his lectures online, for example: drorbn.net/index.php?title=AKT-09 – user641 Apr 8 '13 at 19:52

A very good, more recent introduction to Khovanov homologies was written by Dolotin and Morozov.

Regarding Heegaard Floer: For the "original" theory, I would recommend "Heegaard diagrams and Holomorphic disks" first (not necessarily the whole article...), then "An introduction to Heegaard Floer homology" (both by Ozsvath and Szabo). At least the latter might be a bit difficult as they leave some nontrivial results unexplained. Also perhaps "Combinatorial Heegaard Floer homology and nice diagrams".

There's also a combinatorial HF theory based on a construction from what's called Grid Diagrams. The advantage is that you don't need much of a geometric background (holomorphic disks etc.). On the other hand, you need some advanced algebraic knowledge, and it's also very different from the geometric approach in the articles above, i.e it won't really help you understanding it. For this approach, try "On combinatorial link Floer homology" by Manolescu.