Cyclic regulating balanced Butler groups

A necessary and sufficient condition is derived for an arbitrary cyclic regulating almost completely decomposable group to belong to a K(n)-class, n≥ 0. This allows one to formulate a Structure Theorem for clipped p-primary cyclic regulating groups in each K(n)-class. Using the Indecomposability Criterion we construct an example of an indecomposable balanced Butler group which does not have a unique regulating subgroup. Received: 3 November 1998