A Conformally Invariant Classification Theorem in Four Dimensions

In this paper, we prove a classification theorem of 4-manifolds according to some conformal invariants, which generalizes the conformally invariant sphere theorem of Chang-Gursky-Yang cite{CGY}. Moreover, it provides a four-dimensional analogue of the well-known classification theorem of Schoen-Yau cite{SY2} on 3-manifolds with positive Yamabe invariants.