Local Khovanov homology Talk 2

From ScottWiki

Last week, I told you about Dror Bar-Natan's new formulation of Khovanov homology. However, what I described isn't actually a knot invariant! This week, we'll fix that minor problem.

I'll give a quick reminder of Dror's setup so far (perhaps even self-contained, if you're brave), then we'll look in detail at what makes it tick -- why we need 'cobordism relations' to obtain a knot invariant, what these relations really are, and why we get a knot invariant after we impose them. Perhaps I'll also try to explain Dror's new 'complex simplification' technique, which both makes it computable, and allows even easier proofs of invariance than the ones I'll be showing you.