The automorphism tower of a centerless group (mostly) without choice
Itay Kaplan, Saharon Shelah · arXiv (Cornell University) · 2006
For a centerless group G, we can define its automorphism tower. We define G^{alpha} : G^0=G, G^{alpha +1}=Aut(G^alpha) and for limit ordinals G^delta=bigcup_{alpha ). This situation is generalized by defining ``(G,A) is a special pair''.