2026-02-16

1615: Countably Compact Topological Space

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definition of countably compact topological space

Topics


About: topological space

The table of contents of this article


Starting Context



Target Context


  • The reader will have a definition of countably compact topological space.

Orientation


There is a list of definitions discussed so far in this site.

There is a list of propositions discussed so far in this site.


Main Body


1: Structured Description


Here is the rules of Structured Description.

Entities:
\(*T\): \(\in \{\text{ the topological spaces }\}\)
//

Conditions:
\(\forall \{U_{j'} \in \{\text{ the open subsets of } T\} \vert j' \in J'\}\), where \(J' \in \{\text{ the countable index sets }\}\) and \(\cup_{j' \in J'} U_{j'} = T (\exists J \in \{\text{ the finite subsets of } J'\} (\cup_{j \in J} U_j = T))\)
//


2: Note


\(\{U_{j'} \in \{\text{ the open subsets of } T\} \vert j' \in J'\}\) is called "countable open cover of \(T\)".

Compare with compact topological space.


References


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