| Version 4 |
Version 3 |
| A topological space $X$ is said to be \emph{weakly countably compact} |
A topological space $X$ is said to be \emph{limit point compact} if every infinite subset of $X$ has a limit point. |
| (or \emph{limit point compact}) |
|
| if every infinite subset of $X$ has a limit point. |
|
|
|
| Every countably compact space is weakly countably compact. |
Limit point compactness is equivalent to countable compactness if $X$ is $T_1$ and is equivalent to \PMlinkname{compactness}{Compact} if $X$ is a metric space. |
| The converse is true in \PMlinkname{$\mathrm{T}_1$ spaces}{T1Space}. |
|
|
|
| A metric space is weakly countably compact if and only if it is compact. |
\PMlinkescapeword{compact} |
|
|
| An easy example of a space $X$ |
|
| that is not weakly countably compact |
|
| is any infinite set with the discrete topology. |
|
| A more interesting example is the countable complement topology |
|
| on an uncountable set. |
|