Nice Elongations of Primary Abelian Groups
Danchev, Peter V. ; Keef, Patrick W.
Publ. Mat., Tome 54 (2010) no. 2, p. 317-339 / Harvested from Project Euclid
Suppose $N$ is a nice subgroup of the primary abelian group $G$ and $A=G/N$. The paper discusses various contexts in which $G$ satisfying some property implies that $A$ also satisfies the property, or visa versa, especially when $N$ is countable. For example, if $n$ is a positive integer, $G$ has length not exceeding $\omega_1$ and $N$ is countable, then $G$ is $n$-summable if $A$ is $n$-summable. When $A$ is separable and $N$ is countable, we discuss the condition that any such $G$ decomposes into the direct sum of a countable and a separable group, and we show that it is undecidable in ZFC whether this condition implies that $A$ must be a direct sum of cyclics. We also relate these considerations to the study of nice bases for primary abelian groups.
Publié le : 2010-05-15
Classification:  Nice subgroups,  elongations,  abelian groups,  $\omega_1$-homomorphisms,  20K10
@article{1277731535,
     author = {Danchev, Peter V. and Keef, Patrick W.},
     title = {Nice Elongations of Primary Abelian Groups},
     journal = {Publ. Mat.},
     volume = {54},
     number = {2},
     year = {2010},
     pages = { 317-339},
     language = {en},
     url = {http://dml.mathdoc.fr/item/1277731535}
}
Danchev, Peter V.; Keef, Patrick W. Nice Elongations of Primary Abelian Groups. Publ. Mat., Tome 54 (2010) no. 2, pp.  317-339. http://gdmltest.u-ga.fr/item/1277731535/