Some ugly aleph_1-free abelian groups
逻辑
2007-05-23 v1 群论
摘要
Given an aleph_1-free abelian group G we characterize the class C_G of all torsion abelian groups T satisfying Ext(G,T)=0 assuming the continuum hypothesis CH. Moreover, in Godel's constructable universe we prove that this characterizes C_G for arbitrary torsion-free abelian G. It follows that there exist some ugly aleph_1-free abelian groups.
引用
@article{arxiv.math/0107208,
title = {Some ugly aleph_1-free abelian groups},
author = {Saharon Shelah and Lutz Strüngmann},
journal= {arXiv preprint arXiv:math/0107208},
year = {2007}
}