There has recently been an uptick in citations to my paper [1].  Several works over the years ([2], [3], [4]) have given proofs of my theorem that are easier to understand and more informative, so I have posted a package here that contains the original paper, a correction I published later, and the references below.  Malfait’s article in particular embeds my exact sequence into a remarkable cube of exact sequences.

[1] Charles Wells, Automorphisms of group extensions, Trans. Amer. Math. Soc, 155 (1970), 189-194.

[2] Kung Wei Yang, Isomorphisms of group extensions.  Pacific J. Math. Volume 50, Number 1 (1974), 299-304.

[3] D.J.S. Robinson, Applications of cohomology to the theory of groups, Groups – St. Andrews 1981, London Math. Soc. Lecture Notes vol. 71 (1982), pp. 46–80.

[4] Wim Malfait, The (outer) automorphism group of a group extension.   Bull. Belg. Math Soc. 9 (2002), 361-372.

Send to Kindle