I am interesting in Group Theory. I am a fan of John G. Thompson. I have collected many Thompson's published papsers. I alos hope to collect his unpublished notes, letters etc.
About unpublished lecture notes of Philip Hall
asked Mar 19 '12 at 7:21
Prove that if $A \vartriangleleft G$ is abelian, then $A$ has a complement in $G$.