Abelian Subgroup Separability of Certain Generalized Free Products of Groups

We prove that generalized free products of certain abelian subgroup separable groups are abelian subgroup separable. Applying this, we show that tree products of polycyclic-by-finite groups, amalgamating central subgroups or retracts are abelian subgroup separable.

DOUBLE COSETS IN FREE PRODUCT

This paper deals with problems connecting with decomposition of groups into double cosets. It is established a relation between double decomposition and usual decomposition by subgroups for groups which can be decompose into a generalized free products and groups with free complementarity of subgroups. В статье обсуждаются вопросы, связанные с разложением группы на двойные смежные классы. Для групп, разложимых в обобщенное свободное произведение, и групп со свободно дополняемыми подгруппами устанавливается связь двойного разложения с обычным разложением по подгруппе.

On the Root-Class Residuallity of Generalized Free Products

Let K be a root class of groups. It is proved that a free product of any family of residually K groups with one amalgamated subgroup, which is a retract in all free factors, is residually K. The sufficient condition for a generalized free product of two groups to be residually K is also obtained, provided that the amalgamated subgroup is normal in one of the free factors and is a retract in another.