Extensible automorphism

You might be looking for:

• extensible equals inner: A proof that every extensible automorphism of a group is an inner automorphism. An automorphism $\sigma$ of a group $G$ is termed extensible if for any group $H$ containing $G$, there exists an automorphism $\sigma'$ of $H$ whose restriction to $G$ equals $\sigma$.
• extensible automorphisms problem: A discussion of extensibility of automorphisms and related questions.
• group property-conditionally extensible automorphism: The property of an automorphism being extensible with respect to a group property.
• variety-extensible automorphism: extensibility with respect to a variety of algebras.

Also check out quotient-pullbackable automorphism.