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math.GR2000
GCH implies the existence of many rigid almost free abelian groups
Rüdiger Göbel, Saharon Shelah
We begin with the existence of groups with trivial duals for cardinals aleph_n (n in omega). Then we derive results about strongly aleph_n-free abelian groups of cardinality aleph_…
math.GR2000
Philip Hall's Problem On Non-Abelian Splitters
Rüdiger Göbel, Saharon Shelah
Philip Hall raised around 1965 the following question which is stated in the Kourovka Notebook: Is there a non-trivial group which is isomorphic with every proper extension of itse…
math.GR2000
Localizations of Groups
Rüdiger Göbel, Saharon Shelah
A group homomorphism eta:A-> H is called a localization of A if every homomorphism phi:A-> H can be `extended uniquely' to a homomorphism Phi:H-> H in the sense that Phi eta = phi.…