Abstract
A closed topological n-manifold M n is of S 1-category 2 if it can be covered by two open subsets W 1, W 2 such that the inclusions W i → M n factor homotopically through maps W i → S 1. We show that for n > 3 the fundamental group of such an n-manifold is either trivial or infinite cyclic.
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Dedicated to José María Montesinos on the occasion of his 65th birthday.
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Gómez-Larrañaga, J.C., González-Acuña, F. & Heil, W. Manifolds with S 1-category 2 have cyclic fundamental groups. Math. Z. 266, 783–788 (2010). https://doi.org/10.1007/s00209-009-0598-4
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DOI: https://doi.org/10.1007/s00209-009-0598-4