One Cannot Show from ZFC that there is an Ulm-Type Classification of the Countable Torsion-Free Abelian Groups

  • Garvin Melles
Conference paper
Part of the Mathematical Sciences Research Institute Publications book series (MSRI, volume 26)


Using generalized recursive set functions, we define some notions of classification and prove that if the universe has a Cohen real over L, then there is no Ulm-type classification of the countable torsion-free abelian groups.


Choice Function Recursive Function Countable Model Main Lemma Isomorphism Type 
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Copyright information

© Springer-Verlag New York, Inc. 1992

Authors and Affiliations

  • Garvin Melles
    • 1
  1. 1.Institute of MathematicsThe Hebrew UniversityJerusalemIsrael

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