MATHEMATICA BOHEMICA, Vol. 126, No. 3, pp. 649-652 (2001)

Pure subgroups

Ladislav Bican

Ladislav Bican, KA MFF UK, Sokolovska 83, 186 75 Praha 8, Czech Republic, e-mail:

Abstract: Let $\lambda $ be an infinite cardinal. Set $\lambda _0=\lambda $, define $\lambda _{i+1}=2^{\lambda _i}$ for every $i=0,1,\dots $, take $\mu $ as the first cardinal with $\lambda _i<\mu $, $i=0,1,\dots $ and put $\kappa = (\mu ^{\aleph _0})^+$. If $F$ is a torsion-free group of cardinality at least $\kappa $ and $K$ is its subgroup such that $F/K$ is torsion and $|F/K|\leq \lambda $, then $K$ contains a non-zero subgroup pure in $F$. This generalizes the result from a previous paper dealing with $F/K$ $p$-primary. \endabstract

Keywords: torsion-free abelian groups, pure subgroup, $P$-pure subgroup

Classification (MSC2000): 20K20

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