منابع مشابه
On co-Hopfian nilpotent groups
We characterize co-Hopfian finitely generated torsion free nilpotent groups in terms of their Lie algebra automorphisms, and construct many examples of such groups.
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Let B n be the braid group on n 4 strands. We prove that B n modulo its center is co-Hoppan. We then show that any injective endomorphism of B n is geometric in the sense that it is induced by a homeomorphism of a punctured disk. We further prove that any injection from B n to B n+1 is geometric for n 7. Additionally, we obtain analogous results for mapping class groups of punctured spheres. Th...
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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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ژورنال
عنوان ژورنال: Journal of Algebra
سال: 1971
ISSN: 0021-8693
DOI: 10.1016/0021-8693(71)90028-7