... R1, finite and ´etale, parametriz-ing reductions to G/Z.Recall that all schemes considered in this article are locally of finite type over Spec C. In this section and the following we are going ... appeared naturally in theGieseker-Maruyama construction of the moduli space of (semi)stable sheaves,the condition of (semi)stability of a sheaf F being that all balanced filtrationsof F have negative ... (see [J] for instance, recalled in Section 5).Definition 0.20 (Algebra filtration). A filtration E•⊂ E of a Lie algebrasheaf (E,[, ]) is called an algebra filtration if for all i, j,[Ei,Ej]...