Published online by Cambridge University Press: 22 January 2016
In this paper we shall determine KSO-groups for 4-dimensional CW-complexes by their cohomology rings. We denote by KSO(X) the group of orientable stable vector bundles over X. In 1959 A. Dold and H. Whitney [1] gave the classification of SO(n)-bundles over a 4-complex. It seems, however, to the authors that group structures of them are unknown. We shall give another definition of the difference bundles defined in [1], and we determine the group structure of KSO(X).