A spanning tree model for Khovanov homology

We use a spanning tree model to prove a result of E. S. Lee on the support of Khovanov homology of alternating knots.Comment: 13 pages, 3 figures; Footnote 1 was changed, a remark was rephrased as a theorem, a reference was added, typos were correcte

Khovanov Homology and Conway Mutation

We present an easy example of mutant links with different Khovanov homology. The existence of such an example is important because it shows that Khovanov homology cannot be defined with a skein rule similar to the skein relation for the Jones polynomial.Comment: 9 pages, 5 figure