On general concept of basic subgroups. II.
This paper investigates the productivity of the Zariski topology of a group . If is a family of groups, and is their direct product, we prove that . This inclusion can be proper in general, and we describe the doubletons of abelian groups, for which the converse inclusion holds as well, i.e., . If is the identity element of a group , we also describe the class of groups such that is an elementary algebraic subset of for every group . We show among others, that is stable...
An exact sequence of torsion-free abelian groups is quasi-balanced if the induced sequence is exact for all rank-1 torsion-free abelian groups . This paper sets forth the basic theory of quasi-balanced sequences, with particular attention given to the case in which is a Butler group. The special case where is almost completely decomposable gives rise to a descending chain of classes of Butler groups. This chain is a generalization of the chain of Kravchenko classes that arise from balanced...
A submodule of a -primary module of bounded order is known to be regular if and have simultaneous bases. In this paper we derive necessary and sufficient conditions for regularity of a submodule.