On the second cohomology group of a simplicial group
Sebastian Thomas
Homology, Homotopy and Applications 12(2) (2010), pp. 167-210.
We give an algebraic proof for the result of Eilenberg and Mac Lane that the second cohomology group of a simplicial group G can be computed as a quotient of a fibre product involving the first two homotopy groups and the first Postnikov invariant of G. Our main tool is the theory of crossed module extensions of groups.
fulltext∗, arXiv:0911.2864, journal, MR2721034, Zbl 1203.55011
∗ Extended version.
