))=0,j>0$.  Let $V_i \otimes \cal O_{Q_i \times X} \to \cal F_i$ be the universal quotient, and $\cal K_i$ the universal subsheaf. If we choose a sufficiently large integer $n$ and a suitable $N_i$, then all $\mu$-semi-stable sheaves which satisfy (ii) are parametrized by $Q_i$. We set $