Editing Whitehead problem (section)

{{Distinguish|Whitehead theorem|Whitehead conjecture}}
{{Use shortened footnotes|date=May 2021}}  
In [[group theory]], a branch of [[abstract algebra]], the '''Whitehead problem''' is the following question:

{{quote|1=Is every [[abelian group]] ''A'' with [[Ext functor|Ext]]<sup>1</sup>(''A'', '''Z''') = 0 a [[free abelian group]]?}}

[[Saharon Shelah]] proved that Whitehead's problem is [[Independence (mathematical logic)|independent]] of [[ZFC]], the standard axioms of set theory.{{r|Shelah1974}}