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Topology Proceedings - topo.auburn.edu
... every image of a discrete space under a closed continuous map is discrete, Arhangel’skii and Gordienko describe a relatively locally finite Hausdorff space and a closed continuous mapping from this space onto the convergent sequence space, which is not relatively locally finite. Because every image ...
... every image of a discrete space under a closed continuous map is discrete, Arhangel’skii and Gordienko describe a relatively locally finite Hausdorff space and a closed continuous mapping from this space onto the convergent sequence space, which is not relatively locally finite. Because every image ...
3-manifold
![](https://commons.wikimedia.org/wiki/Special:FilePath/3-Manifold_3-Torus.png?width=300)
In mathematics, a 3-manifold is a space that locally looks like Euclidean 3-dimensional space. Intuitively, a 3-manifold can be thought of as a possible shape of the universe. Just like a sphere looks like a plane to a small enough observer, all 3-manifolds look like our universe does to a small enough observer. This is made more precise in the definition below.