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math.LO2000
Whitehead modules over large principal ideal domains
Paul C. Eklof, Saharon Shelah
We consider the Whitehead problem for principal ideal domains of large size. It is proved, in ZFC, that some p.i.d.'s of size >= aleph_{2} have non-free Whitehead modules even thou…
math.LO2000
On Whitehead precovers
Paul C. Eklof, Saharon Shelah
It is proved undecidable in ZFC + GCH whether every Z-module has a^{perp} {Z}-precover.
math.LO2000
Absolutely rigid systems and absolutely indecomposable groups
Paul C. Eklof, Saharon Shelah
We give a new proof that there are arbitrarily large indecomposable abelian groups; moreover, the groups constructed are absolutely indecomposable, that is, they remain indecomposa…