Whitehead problem

Not to be confused with Whitehead theorem or Whitehead conjecture.

In group theory, a branch of abstract algebra, the Whitehead problem is the following question:

Is every abelian group A with Ext1(A, Z) = 0 a free abelian group?

Saharon Shelah proved that Whitehead's problem is independent of ZFC, the standard axioms of set theory.[1]

  1. ^ Cite error: The named reference Shelah1974 was invoked but never defined (see the help page).