= Principal Eilenberg–MacLane fibration
{title2=$K(A,n)\to E\to B$}
= Principal fibration with Eilenberg–MacLane fibre
{synonym}
For an abelian group $A$, a principal fibration with fibre $K(A,n)$ is a <homotopy pullback> of the <path fibration> $PK(A,n+1)\to K(A,n+1)$. It is therefore the <homotopy fibre> of a map $k:B\to K(A,n+1)$ and is classified by $[k]\in H^{n+1}(B;A)$. The fibre acts by translation up to <homotopy>; in this untwisted description the <fundamental group> acts trivially on $A$. This is the principal-fibration form used for <simply connected> <Postnikov towers>.
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