Hopfian and strongly hopfian manifolds
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چکیده
Let p : M → B be a proper surjective map defined on an (n+ 2)-manifold such that each point-preimage is a copy of a hopfian n-manifold. Then we show that p is an approximate fibration over some dense open subset O of the mod 2 continuity set C′ and C′ \O is locally finite. As an application, we show that a hopfian n-manifold N is a codimension-2 fibrator if χ(N) 6= 0 or H1(N) ∼= Z2.
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