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	<id>https://topospaces.subwiki.org/w/index.php?action=history&amp;feed=atom&amp;title=Hausdorffness_is_refining-preserved</id>
	<title>Hausdorffness is refining-preserved - Revision history</title>
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	<updated>2026-09-09T14:12:08Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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	<entry>
		<id>https://topospaces.subwiki.org/w/index.php?title=Hausdorffness_is_refining-preserved&amp;diff=4499&amp;oldid=prev</id>
		<title>Vipul at 04:37, 30 January 2014</title>
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		<updated>2014-01-30T04:37:41Z</updated>

		<summary type="html">&lt;p&gt;&lt;/p&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 04:37, 30 January 2014&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l1&quot;&gt;Line 1:&lt;/td&gt;
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&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;{{topospace metaproperty satisfaction}}&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;{{topospace metaproperty satisfaction&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;|property = Hausdorff space|metaproperty = refining-preserved property of topological spaces&lt;/ins&gt;}}&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[Difficulty level::1| ]]&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Statement==&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Statement==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
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&lt;/table&gt;</summary>
		<author><name>Vipul</name></author>
	</entry>
	<entry>
		<id>https://topospaces.subwiki.org/w/index.php?title=Hausdorffness_is_refining-preserved&amp;diff=2627&amp;oldid=prev</id>
		<title>Vipul at 16:21, 21 July 2008</title>
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		<updated>2008-07-21T16:21:34Z</updated>

		<summary type="html">&lt;p&gt;&lt;/p&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 16:21, 21 July 2008&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l1&quot;&gt;Line 1:&lt;/td&gt;
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&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Statement==&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;==Statement==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Vipul</name></author>
	</entry>
	<entry>
		<id>https://topospaces.subwiki.org/w/index.php?title=Hausdorffness_is_refining-preserved&amp;diff=2626&amp;oldid=prev</id>
		<title>Vipul: New page: {{topospace metaproperty satisaction}}  ==Statement==  ===Property-theoretic statement===  The property of topological spaces of being a Hausdorff space ===Statement with symbols==...</title>
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		<updated>2008-07-21T16:20:14Z</updated>

		<summary type="html">&lt;p&gt;New page: {{topospace metaproperty satisaction}}  ==Statement==  ===Property-theoretic statement===  The &lt;a href=&quot;/wiki/Property_of_topological_spaces&quot; title=&quot;Property of topological spaces&quot;&gt;property of topological spaces&lt;/a&gt; of being a &lt;a href=&quot;/wiki/Hausdorff_space&quot; title=&quot;Hausdorff space&quot;&gt;Hausdorff space&lt;/a&gt; ===Statement with symbols==...&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;{{topospace metaproperty satisaction}}&lt;br /&gt;
&lt;br /&gt;
==Statement==&lt;br /&gt;
&lt;br /&gt;
===Property-theoretic statement===&lt;br /&gt;
&lt;br /&gt;
The [[property of topological spaces]] of being a [[Hausdorff space]]&lt;br /&gt;
===Statement with symbols===&lt;br /&gt;
&lt;br /&gt;
Suppose &amp;lt;math&amp;gt;(X,\tau)&amp;lt;/math&amp;gt; is a topological space and &amp;lt;math&amp;gt;\tau&amp;#039;&amp;lt;/math&amp;gt; is a [[finer topology]] on &amp;lt;math&amp;gt;X&amp;lt;/math&amp;gt; than &amp;lt;math&amp;gt;\tau&amp;lt;/math&amp;gt;.&lt;br /&gt;
&lt;br /&gt;
==Proof==&lt;br /&gt;
&lt;br /&gt;
&amp;#039;&amp;#039;&amp;#039;Given&amp;#039;&amp;#039;&amp;#039;: A Hausdorff topological space &amp;lt;math&amp;gt;(X,\tau)&amp;lt;/math&amp;gt;, and a topology &amp;lt;math&amp;gt;\tau&amp;#039;&amp;lt;/math&amp;gt; on &amp;lt;math&amp;gt;X&amp;lt;/math&amp;gt; that is [[finer topology|finer]] than &amp;lt;math&amp;gt;\tau&amp;lt;/math&amp;gt;&lt;br /&gt;
&lt;br /&gt;
&amp;#039;&amp;#039;&amp;#039;To prove&amp;#039;&amp;#039;&amp;#039;: &amp;lt;math&amp;gt;(X,\tau&amp;#039;)&amp;lt;/math&amp;gt; is Hausdorff&lt;br /&gt;
&lt;br /&gt;
&amp;#039;&amp;#039;&amp;#039;Proof&amp;#039;&amp;#039;&amp;#039;: We need to show that for points &amp;lt;math&amp;gt;x \ne y&amp;lt;/math&amp;gt; in &amp;lt;math&amp;gt;X&amp;lt;/math&amp;gt;, there exist open sets &amp;lt;math&amp;gt;U,V&amp;lt;/math&amp;gt; in the topology &amp;lt;math&amp;gt;\tau&amp;#039;&amp;lt;/math&amp;gt; such that &amp;lt;math&amp;gt;x \in U, y \in V&amp;lt;/math&amp;gt;, and &amp;lt;math&amp;gt;U \cap V&amp;lt;/math&amp;gt; is empty.&lt;br /&gt;
&lt;br /&gt;
Since &amp;lt;math&amp;gt;\tau&amp;lt;/math&amp;gt; gives a Hausdorff topology, we can find open sets &amp;lt;math&amp;gt;U,V&amp;lt;/math&amp;gt; in the topology &amp;lt;math&amp;gt;\tau&amp;lt;/math&amp;gt;, such that &amp;lt;math&amp;gt;x \in U, y \in V&amp;lt;/math&amp;gt; and &amp;lt;math&amp;gt;U \cap V&amp;lt;/math&amp;gt; is empty. And since &amp;lt;math&amp;gt;\tau&amp;#039;&amp;lt;/math&amp;gt; is finer than &amp;lt;math&amp;gt;\tau&amp;lt;/math&amp;gt;, the sets &amp;lt;math&amp;gt;U,V&amp;lt;/math&amp;gt; satisfy the condition in &amp;lt;math&amp;gt;\tau&amp;#039;&amp;lt;/math&amp;gt; as well.&lt;/div&gt;</summary>
		<author><name>Vipul</name></author>
	</entry>
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