Compactness of moduli spaces for orbifold instantons (Q1114970)

Many questions related to 3- and 4-dimensional topology can be expressed in terms of certain singular spaces dubbed `pseudofree orbifolds'. A successful technique for studying these spaces is to examine the moduli spaces of self-dual connections on (orbifold) bundles over them, and a theorem of Fintushel and Stern shows that these moduli spaces must be compact when the corresponding bundle has small enough Pontryagin number. The purpose of this article is to show how this compactness range can be considerably extended for purely equivariant topological reasons.