Homotopy dimension and simple cohomological dimension of spaces.
En définissant une nouvelle classe de nœuds dans les variétés de dimension 3, on obtient une démonstration plus classique du théorème de rigidité virtuelle des variétés hyperboliques de D. Gabai.
Given a cohomology class there is a smooth submanifold Poincaré dual to . A special class of such embeddings is characterized by topological properties which hold for nonsingular algebraic hypersurfaces in . This note summarizes some results on the question: how does the divisibility of restrict the dual submanifolds in this class ? A formula for signatures associated with a -fold ramified cover of branched along is given and a proof is included in case .
In this note, a topological version of the results obtained, in connection with the de Rham reducibility theorem (Comment. Math. Helv., 26 ( 1952), 328–344), by S. Kashiwabara (Tôhoku Math. J., 8 (1956), 13–28), (Tôhoku Math. J., 11 (1959), 327–350) and Ia. L. Sapiro (Izv. Bysh. Uceb. Zaved. Mat. no6, (1972), 78–85, Russian), (Izv. Bysh. Uceb. Zaved. Mat. no4, (1974), 104–113, Russian) is given. Thus a characterization of a class of topological spaces covered by a product space is obtained and the...
We prove several results concerning the existence of universal covering spaces for separable metric spaces. To begin, we define several homotopy-theoretic conditions which we then prove are equivalent to the existence of a universal covering space. We use these equivalences to prove that every connected, locally path connected separable metric space whose fundamental group is a free group admits a universal covering space. As an application of these results, we prove the main result of this article,...