Abstract
We exhibit a maximal set of 2N0 “almost rigid” countable mixed abelian groupsG with the same prescribed torsion subgroupstG, the same quotientG/tG and a fixed countable and cotorsion-free ringA such that EndG/Hom(G, tG)≌A. Despite the fact that these candidates will not allow any structure theorem, they are close relatives of the well-behaving family of Warfield groups. The results are developed in a module category for suitable ground rings.
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Dugas, M., Göbel, R. Countable mixed Abelian groups with very nice full-rank subgroups. Israel J. Math. 51, 1–12 (1985). https://doi.org/10.1007/BF02772953
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DOI: https://doi.org/10.1007/BF02772953