Page 1 Next

Displaying 1 – 20 of 28

Showing per page

On Butler B ( 2 ) -groups decomposing over two base elements

Clorinda de Vivo, Claudia Metelli (2009)

Commentationes Mathematicae Universitatis Carolinae

A B ( 2 ) -group is a sum of a finite number of torsionfree Abelian groups of rank 1 , subject to two independent linear relations. We complete here the study of direct decompositions over two base elements, determining the cases where the relations play an essential role.

On countable extensions of primary abelian groups

Peter Vassilev Danchev (2007)

Archivum Mathematicum

It is proved that if A is an abelian p -group with a pure subgroup G so that A / G is at most countable and G is either p ω + n -totally projective or p ω + n -summable, then A is either p ω + n -totally projective or p ω + n -summable as well. Moreover, if in addition G is nice in A , then G being either strongly p ω + n -totally projective or strongly p ω + n -summable implies that so is A . This generalizes a classical result of Wallace (J. Algebra, 1971) for totally projective p -groups as well as continues our recent investigations in (Arch....

On direct sums of ( 1 ) -groups

Claudia Metelli (1993)

Commentationes Mathematicae Universitatis Carolinae

A necessary and sufficient condition is given for the direct sum of two ( 1 ) -groups to be (quasi-isomorphic to) a ( 1 ) -group. A ( 1 ) -group is a torsionfree Abelian group that can be realized as the quotient of a finite direct sum of rank 1 groups modulo a pure subgroup of rank 1.

On extensions of bounded subgroups in Abelian groups

S. S. Gabriyelyan (2014)

Commentationes Mathematicae Universitatis Carolinae

It is well-known that every bounded Abelian group is a direct sum of finite cyclic subgroups. We characterize those non-trivial bounded subgroups H of an infinite Abelian group G , for which there is an infinite subgroup G 0 of G containing H such that G 0 has a special decomposition into a direct sum which takes into account the properties of G , and which induces a natural decomposition of H into a direct sum of finite subgroups.

Currently displaying 1 – 20 of 28

Page 1 Next