2000/03/20 by Winfried Just, Saharon Shelah, Simon Thomas
Mathematics · #math.LO #math.GR
published as Advances in Mathematics, 148(1999):243-265
arxiv created 2000/03/20 · arxiv updated 2009/11/30
It is well-known that the automorphism towers of infinite centreless groups of cardinality kappa terminate in less than (2kappa)+ steps. But an easy counting argument shows that (2kappa)+ is not the best possible bound. However, in this paper, we will show that it is impossible to find an explicit better bound using ZFC.