  We define a link homology theory that is readily seen to be both isomorphic
to reduced odd Khovanov homology and fully determined by data impervious to
Conway mutation. This gives an elementary proof that odd Khovanov homology is
mutation invariant, and therefore that mod 2 Khovanov homology is mutation
invariant. We also establish mutation invariance for the entire Ozsvath-Szabo
spectral sequence from reduced Khovanov homology to the Heegaard Floer homology
of the branched double cover.
