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author | Justin Gassner <justin.gassner@mailbox.org> | 2024-02-14 07:24:38 +0100 |
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committer | Justin Gassner <justin.gassner@mailbox.org> | 2024-02-14 07:24:38 +0100 |
commit | 28407333ffceca9b99fae721c30e8ae146a863da (patch) | |
tree | 67fa2b79d5c48b50d4e394858af79c88c1447e51 /pages/general-topology/baire-spaces.md | |
parent | 777f9d3fd8caf56e6bc6999a4b05379307d0733f (diff) | |
download | site-28407333ffceca9b99fae721c30e8ae146a863da.tar.zst |
Update
Diffstat (limited to 'pages/general-topology/baire-spaces.md')
-rw-r--r-- | pages/general-topology/baire-spaces.md | 35 |
1 files changed, 15 insertions, 20 deletions
diff --git a/pages/general-topology/baire-spaces.md b/pages/general-topology/baire-spaces.md index 6bd7d9f..1332984 100644 --- a/pages/general-topology/baire-spaces.md +++ b/pages/general-topology/baire-spaces.md @@ -1,25 +1,24 @@ --- title: Baire Spaces parent: General Topology -nav_order: 1 +nav_order: 7 description: > A Baire space is a topological space with the property that the intersection of countably many dense open subsets is still dense. One version of the Baire Category Theorem states that complete metric spaces are Baire spaces. We give a self-contained proof of Baire's Category Theorem by contradiction. -# spellchecker:words --- # {{ page.title }} -{: .definition } -> A topological space is said to be a *Baire space*, -> if any of the following equivalent conditions holds: -> {: .mb-0 } -> -> - The intersection of countably many dense open subsets is still dense. -> - The union of countably many closed subsets with empty interior has empty interior. -> {: .mt-0 .mb-0 } +{% definition Baire Space %} +A topological space is said to be a *Baire space*, +if any of the following equivalent conditions holds: +{: .mb-0 } + +- The intersection of countably many dense open subsets is still dense. +- The union of countably many closed subsets with empty interior has empty interior. +{% enddefinition %} Note that a set is dense in a topological space @@ -33,11 +32,9 @@ of which there are several. Here we give one that is commonly used in functional analysis. -{: .theorem-title } -> Baire Category Theorem #1 -> {: #baire-category-theorem } -> -> Every complete metric space is a Baire space. +{% theorem * Baire Category Theorem #1 %} +Every complete metric space is a Baire space. +{% endtheorem %} {% proof %} Let $X$ be a metric space @@ -76,8 +73,6 @@ On the other hand, $x \in \overline{B_1} \subset X \setminus U$, in contradiction to the preceding statement. {% endproof %} -{: .theorem-title } -> Baire Category Theorem #2 -> {: #baire-category-theorem } -> -> Every compact Hausdorff space is a Baire space. +{% theorem * Baire Category Theorem #2 %} +Every locally compact Hausdorff space is a Baire space. +{% endtheorem %} |