| | Encyclopedia article on Topological space [EncycloZine] (Site not responding. Last check: 2007-10-18) |
 | | The category of topological spaces, Top, with topological spaces as objects and continuous functions as morphisms is one of the fundamental categories in mathematics. |
 | | The attempt to classify the objects of this category by invariants has motivated and generated entire areas of research, such as homotopy theory, homology theory, and K-theory, to name just a few. |
 | | Non-empty ultra-connected compact spaces have a largest proper open subset called a monolith. |
| encyclozine.com /Topological_space (2350 words) |