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The group of homotopy self-equivalences of non-simply-connected spaces using Postnikov decompositions*
Published online by Cambridge University Press: 14 November 2011
Synopsis
We give here a group extension sequence for calculating, for a non-simply-connected space X, the group of self-homotopy-equivalence classes which induce the identity automorphism of the fundamental group, that is the kernel of the representation
→ aut (π1(X)). This group extension sequence gives
in terms of
, where Xn is the n-th stage of a Postnikov decomposition. As special cases, we calculate
for non-simply-connected spaces having at most two non-trivial homotopy groups, in dimensions 1 and n, as the unit group of a semigroup structure on
; and we calculate
up to extension for non-simply-connected spaces having at most three non-trivial homotopy groups. The group
is, for nice spaces, isomorphic to the groups
and
of self-homotopy-equivalence classes of X in the categories top*M and top M, respectively, where X→M = K1(π1(X)) is a top fibration which determines an isomorphism of the fundamental group; and our results are obtained initially in topM.
- Type
- Research Article
- Information
- Proceedings of the Royal Society of Edinburgh Section A: Mathematics , Volume 120 , Issue 1-2 , 1992 , pp. 47 - 60
- Copyright
- Copyright © Royal Society of Edinburgh 1992
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