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P-extensible implies inner
From Groupprops
Statement
Suppose p is a prime number and P is a p-group, i.e., a group in which the order of every element is a power of p. Suppose σ is an automorphism of P such that for any p-group Q containing P, there is an automorphism σ' of Q whose restriction to P equals σ. Then, σ is an inner automorphism of P.
References
Journal references
- Characterizing inner automorphisms of groups by Martin R. Pettet, Archiv der Mathematik, ISSN 1420-8938 (Online), ISSN 0003-889X (Print), Volume 55,Number 5, Page 422 - 428(Year 1990): Springerlink official copyMore info

