Abstract
We consider the class \(\mathcal{Q}\mathcal{D}1\) of mixed abelian quotient divisible groups of torsion-free rank 1. Groups from this class, as well as countable mixed abelian groups of rank 1 are determined by their own torsion part and the class of equivalent height-matrices, which are invariants of such groups. On the other hand, every group from \(\mathcal{Q}\mathcal{D}1\) can be described by its cocharacteristic. An abelian group \(G\) is called a \(TI\) -group if every associative ring on \(G\) is filial. In the class \(\mathcal{Q}\mathcal{D}1\) \(TI\) -groups are described in the language of these invariants.