Abstract
We discuss the prospects for finding a “core class,” i.e., a well-behaved class of non-free abelian groups of cardinality ℵ1 such that every non-free abelian group of cardinality ℵ1 has a subgroup in the core class.
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Acknowledgments
We thank the referee for his helpful comments and in particular for bringing to our attention the references Eklof et al.(Citation1984), and Mekler (Citation1983 Citation1987). Blass was partially supported by NSF grant DMS 0070723.
Notes
#Communicated by K. Rangaswamy.