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1. • CommentRowNumber1.
   • CommentAuthorronniegpd
   • CommentTimeSep 30th 2012
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   Author: ronniegpd
   Format: TextI have added some information on the work of Henry Whitehead which is related to this topic, and referred to work of Graham Ellis, and of Higgins and I, which is relevant. I expect I have not given the best code for all of this so someone may want to improve it in that respect. Graham, also writes in his paper: In view of the ease with which Whitehead's methods handle the classifications of Olum and Jajodia, it is surprising that the papers \cite{olum:1953} and \cite{jaj:1980} (both of which were written after the publication of \cite{whjhc:1949}) make respectively no use, and so little use, of \cite{whjhc:1949}. We note here that B. Schellenberg, who was a student of Olum, has rediscovered in \cite{sch:1973} the main classification theorems of \cite{whjhc:1949}. The paper \cite{sch:1973} relies heavily on earlier work of Olum.

   I have added some information on the work of Henry Whitehead which is related to this topic, and referred to work of Graham Ellis, and of Higgins and I, which is relevant.
   
   I expect I have not given the best code for all of this so someone may want to improve it in that respect.
   
   Graham, also writes in his paper:
   
   In view of the ease with which Whitehead's methods handle the
   classifications of Olum and Jajodia, it is surprising that the
   papers \cite{olum:1953} and \cite{jaj:1980} (both of which were
   written after the publication of \cite{whjhc:1949}) make
   respectively no use, and so little use, of \cite{whjhc:1949}.
   
   We note here that B. Schellenberg, who was a student of Olum, has
   rediscovered in \cite{sch:1973} the main classification theorems
   of \cite{whjhc:1949}. The paper \cite{sch:1973} relies heavily on
   earlier work of Olum.
2. • CommentRowNumber2.
   • CommentAuthorTodd_Trimble
   • CommentTimeSep 30th 2012
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   Author: Todd_Trimble
   Format: MarkdownItexI had trouble detecting the article you added to, before I finally resorted to "Recently Revised": [[history of cohomology with local coefficients]]

   I had trouble detecting the article you added to, before I finally resorted to “Recently Revised”: history of cohomology with local coefficients

3. • CommentRowNumber3.
   • CommentAuthorTim_Porter
   • CommentTimeOct 1st 2012
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   Author: Tim_Porter
   Format: MarkdownItexAt present there seems to be discussion of non-abelian $H^2$ but almost nothing on $H^1$, with or without local coefficients. (I point this out as I am trying to write a section in the monograph I am working on, that makes the link between Serre's definition of non-abelian $H^1(G,A)$ and the corresponding $H^1$ for simplicial profinite spaces. ... and the task is proving difficult at the level I am assuming for the reader!

   At present there seems to be discussion of non-abelian $H^2$ but almost nothing on $H^1$, with or without local coefficients. (I point this out as I am trying to write a section in the monograph I am working on, that makes the link between Serre’s definition of non-abelian $H^1(G,A)$ and the corresponding $H^1$ for simplicial profinite spaces. … and the task is proving difficult at the level I am assuming for the reader!

4. • CommentRowNumber4.
   • CommentAuthorronniegpd
   • CommentTimeOct 1st 2012
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   Author: ronniegpd
   Format: TextTim: I wonder if the notions of "fibrations of groupoids" and "groupoids as coefficients" are relevant: I would like to believe they were! (10 and 11 on my pub list, and downloadable). They both deal with nonabelian cohomology. See also 164. `Exact sequences of fibrations of crossed complexes, homotopy classification of maps, and nonabelian extensions of groups', J. Homotopy and Related Structures 3 (2008) 331-343. for the higher dimensional case.

   Tim: I wonder if the notions of "fibrations of groupoids" and "groupoids as coefficients" are relevant: I would like to believe they were! (10 and 11 on my pub list, and downloadable). They both deal with nonabelian cohomology.
   
   See also 164. `Exact sequences of fibrations of crossed complexes, homotopy
   classification of maps, and nonabelian extensions of groups', J.
   Homotopy and Related Structures 3 (2008) 331-343.
   
   for the higher dimensional case.