Mukai flops and derived categories II

This paper is a sequel to math.AG/0203287. A generalization of the Mukai flop has been studied by E. Markman. Here we call it a stratified Mukai flop. In this paper, we observe that, for a stratified Mukai flop: $X \to \bar{X} \leftarrow X^+$,thefiberproduct$X \times_{\bar{X}}X^+$ defines an isomorphism of Grothendieck groups $K(X)\to K(X^{+})$, but, at the level of derived categories, the fiber product does not generally give an equivalence.