Automorphism, inner and outer groups
Aut(G) consists of group isomorphisms G→G under composition.
Key knowledge
Aut(G) consists of group isomorphisms G→G under composition. Conjugations cₐ(g)=aga⁻¹ form its normal subgroup Inn(G); the map a↦cₐ has kernel Z(G), so Inn(G)≅G/Z(G). The quotient Aut(G)/Inn(G) is Out(G).
Conditions and scope
- These identities do not require G finite.
- An arbitrary bijection of G is not necessarily an automorphism.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Definition-Lemma 23.10 and proof; φcₐφ⁻¹=c_(φ(a)) verifies normality. No S6 classification claim is made.
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Entry details
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- math-group-automorphisms
- Revision
- university-core.1
- Structured reference record
- University core expansion