Journal of the
Korean Mathematical Society JKMS

Approximate fibrations form a useful class of maps. By definition fibrators provide instant detection of maps in this class, and PL fibrators do the same in the PL category. We show that every closed s-hopfian $t$-aspherical manifold $N$ with sparsely Abelian, hopfian fundamental group and $\chi(N) \ne 0$ is a codimension-$(t+1)$ PL fibrator.

Keywords: approximate fibration, degree of a map, codimension-$k$ fibrator, $m$-fibrator, Hopfian manifold, normally cohopfian, sparsely Abelian

MSC numbers: Primary 57N15, 55R65; Secondary 57N25, 54B15