4 papers · 1 filter
On Crawley Modules
Rüdiger Göbel, Saharon Shelah
This continues recent work in a paper by Corner, Gobel and Goldsmith. A particular question was left open: Is it possible to carry over the results concerning the undecidability of…
Characterizing automorphism groups of ordered abelian groups
Rüdiger Göbel, Saharon Shelah
We characterize the groups isomorphic to full automorphism groups of ordered abelian groups. The result will follow from classical theorems on ordered groups adding an argument fro…
Decompositions of Reflexive Modules
Ruediger Goebel, Saharon Shelah
We continue [GbSh:568] (math.LO/0003164), proving a stronger result under the special continuum hypothesis (CH). The original question of Eklof and Mekler related to dual abelian g…
Some Nasty Reflexive Groups
Ruediger Goebel, Saharon Shelah
In "Almost Free Modules, Set-theoretic Methods", Eklof and Mekler raised the question about the existence of dual abelian groups G which are not isomorphic to Z+G. Recall that G is…