The duals of almost completely decomposable groups (Q1358272)

A torsion-free Abelian group is called completely decomposable if it is the direct sum of rank-one groups. \textit{R. Baer} [Duke Math. J. 3, 68-122 (1937; Zbl 0041.27302)] described these groups by numerical invariants. In this interesting paper, the author classifies the direct products of one-dimensional compact connected Abelian groups. Thus he dualizes Baer's theorem. A finite rank torsion-free Abelian group is said to be almost completely decomposable provided it contains a completely decomposable subgroup of finite index. The author gives an isomorphism theorem for the Pontrjagin dual of such groups.