Commutation relations of vertex operators for U_q(widehat{sl}(M|N))

We consider commutation relations and invertibility relations of vertex operators for the quantum affine superalgebra $U_q(\widehat{sl}(M|N))$ by using bosonization. We show that vertex operators give a representation of the graded Zamolodchikov-Faddeev algebra by direct computation.Invertibility relations of type-II vertex operators for $N>M$ are very similar to those of type-I for $M>N$.