For purposes of my own, I'm interested in constructing connected spaces, without recourse to geometric realisation or the like, that have non-trivial homotopy groups in dimension 1 and 2 and are not products of Eilenberg-MacLane spaces. This rules out obvious constructions using crossed modules (at least, obvious to me).
One idea is this: take a representation of , the fundamental group of a compact, connected, orientable surface or genus . Then form the associated sphere bundle .
Then, unless my calculation is wrong, is a 2-type space with , and -invariant .
So my question is,
are there any non-trivial representations or cohomology classes ?
and secondarily,
would a non-trivial representation give rise to a non-trivial -invariant in the above situation?
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