Every automorphism is center-fixing and outer automorphism group is rank one p-group implies not every normal-extensible automorphism is inner
Suppose is a group satisfying both the following conditions:
- , the outer automorphism group, is a nontrivial group having a unique minimal subgroup. In other words, it is a p-group of rank one. (when finite, it is either a cyclic group of prime power order or a generalized quaternion group).
- Every automorphism of is a center-fixing automorphism.
Then, the inverse image in of the unique minimal subgroup of is contained in the group of normal-extensible automorphisms. In particular, not every normal-extensible automorphism is inner.