[ALGTOP-L] Crossed module extensions

Sebastian Thomas sebastian.thomas at rwth-aachen.de
Fri Nov 21 17:22:32 EST 2008

Thanks to everyone who sent me helpful comments via eMail.

The existence of a finite representative can be found in
Graham Ellis: "Spaces with finitely many non-trivial homotopy groups  
all of which are finite", Topology Vol. 36 (1997), 501-504.
(One has to use the well-known bijection between the set of  
equivalence classes and H^3(G, M).)

Sebastian Thomas

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