![A. X s-oonverges to a point p € X (denoted by F](http://s1.studyres.com/store/data/006749560_1-9b00dea14fe18ab8859ef063005690d1-300x300.png)
A. X s-oonverges to a point p € X (denoted by F
... Convergence and accumulation of filterbases in the usual sense, of course, imply s-convergence and s-accumulation, respectively. ...
... Convergence and accumulation of filterbases in the usual sense, of course, imply s-convergence and s-accumulation, respectively. ...
“TOPICS IN MODERN GEOMETRY” TOPOLOGY Introduction This
... (3) Given a subset A ⊂ X, the interior int(A) of A is the union of all open sets contained in E. Many of the standard results follow immediately. Proposition 1.4. Let X be a topological space and let A ⊂ X be a subset. The interior of A is open and the closure of A is closed. Moreover, A is open iff ...
... (3) Given a subset A ⊂ X, the interior int(A) of A is the union of all open sets contained in E. Many of the standard results follow immediately. Proposition 1.4. Let X be a topological space and let A ⊂ X be a subset. The interior of A is open and the closure of A is closed. Moreover, A is open iff ...
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.