* The Cantor set. This is a corollary of the previous example and Tychonoff's Theorem (see below). |
* The Cantor set. |
* A subset of Euclidean n-space is compact if and only if it is closed and bounded. (Heine-Borel Theorem) |
* A subset of Euclidean n-space is compact if and only if it is closed and bounded. (Heine-Borel theorem) |
* A topological space is compact if and only if every filter on the space has a convergent refinement. |
* Pseudocompact: Every real-valued function on the space is bounded. |
* Pseudocompact: Every real-valued continuous function on the space is bounded. |
Compact spaces are countably compact, as are sequentially compact spaces. Countably compact spaces are pseudocompact and weakly countably compact. |
While all these concepts are equivalent for metric spaces, in general we have the following implications: Compact spaces are countably compact. Sequentially compact spaces are countably compact. Countably compact spaces are pseudocompact and weakly countably compact. /Talk? |