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	<title>Foundations of geometry - Revision history</title>
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	<updated>2026-04-09T05:02:56Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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	<entry>
		<id>https://en.formulasearchengine.com/index.php?title=Foundations_of_geometry&amp;diff=23621&amp;oldid=prev</id>
		<title>en&gt;BattyBot: fixed CS1 errors: dates &amp; General fixes using AWB (9803)</title>
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		<updated>2013-12-23T10:42:32Z</updated>

		<summary type="html">&lt;p&gt;fixed &lt;a href=&quot;/index.php?title=Category:CS1_errors:_dates&amp;amp;action=edit&amp;amp;redlink=1&quot; class=&quot;new&quot; title=&quot;Category:CS1 errors: dates (page does not exist)&quot;&gt;CS1 errors: dates&lt;/a&gt; &amp;amp; &lt;a href=&quot;/index.php?title=WP:AWB/GF&amp;amp;action=edit&amp;amp;redlink=1&quot; class=&quot;new&quot; title=&quot;WP:AWB/GF (page does not exist)&quot;&gt;General fixes&lt;/a&gt; using &lt;a href=&quot;/index.php?title=Testwiki:AWB&amp;amp;action=edit&amp;amp;redlink=1&quot; class=&quot;new&quot; title=&quot;Testwiki:AWB (page does not exist)&quot;&gt;AWB&lt;/a&gt; (9803)&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;&amp;#039;&amp;#039;&amp;#039;[[wiktionary:fr:balayage|Balayage]]&amp;#039;&amp;#039;&amp;#039; is a [[French language|French]] word meaning scanning or sweeping.&lt;br /&gt;
&lt;br /&gt;
In [[potential theory]], a mathematical discipline, &amp;#039;&amp;#039;&amp;#039;balayage&amp;#039;&amp;#039;&amp;#039; is a method devised by [[Henri Poincaré]] for reconstructing a [[harmonic function]] in a domain from its values on the boundary of the domain.&amp;lt;ref&amp;gt;{{SpringerEOM| title=Balayage method | id=Balayage_method | oldid=11819 | first=E.D. | last=Solomentsev }}&amp;lt;/ref&amp;gt; &lt;br /&gt;
&lt;br /&gt;
In modern terms, the &amp;#039;&amp;#039;&amp;#039;balayage operator&amp;#039;&amp;#039;&amp;#039; maps a [[Measure (mathematics)|measure]] &amp;#039;&amp;#039;&amp;amp;mu;&amp;#039;&amp;#039; on a closed domain &amp;#039;&amp;#039;D&amp;#039;&amp;#039; to a measure &amp;#039;&amp;#039;&amp;amp;nu;&amp;#039;&amp;#039; on the boundary &amp;#039;&amp;#039;&amp;amp;part; D&amp;#039;&amp;#039;, so that the [[Newtonian potential]]s of &amp;#039;&amp;#039;&amp;amp;mu;&amp;#039;&amp;#039; and &amp;#039;&amp;#039;&amp;amp;nu;&amp;#039;&amp;#039; coincide outside &amp;#039;&amp;#039;D&amp;#039;&amp;#039;. The procedure is called balayage since the massed is &amp;quot;sweeped out&amp;quot; from &amp;#039;&amp;#039;D&amp;#039;&amp;#039; onto the boundary.&lt;br /&gt;
&lt;br /&gt;
For &amp;#039;&amp;#039;x&amp;#039;&amp;#039; in &amp;#039;&amp;#039;D&amp;#039;&amp;#039;, the balayage of [[Dirac delta function|&amp;#039;&amp;#039;&amp;amp;delta;&amp;#039;&amp;#039;&amp;lt;sub&amp;gt;&amp;#039;&amp;#039;x&amp;#039;&amp;#039;&amp;lt;/sub&amp;gt;]] yields the [[harmonic measure]] &amp;#039;&amp;#039;&amp;amp;nu;&amp;#039;&amp;#039;&amp;lt;sub&amp;gt;&amp;#039;&amp;#039;x&amp;#039;&amp;#039;&amp;lt;/sub&amp;gt; corresponding to &amp;#039;&amp;#039;x&amp;#039;&amp;#039;. Then the value of a harmonic function &amp;#039;&amp;#039;f&amp;#039;&amp;#039; at &amp;#039;&amp;#039;x&amp;#039;&amp;#039; is equal to&lt;br /&gt;
&lt;br /&gt;
:&amp;lt;math&amp;gt; f(x) = \int_{\partial D} f(y) \, d\nu_x(y).&amp;lt;/math&amp;gt;&lt;br /&gt;
&lt;br /&gt;
== References ==&lt;br /&gt;
&amp;lt;references/&amp;gt;&lt;br /&gt;
&lt;br /&gt;
{{DEFAULTSORT:Balayage}}&lt;br /&gt;
[[Category:Potential theory]]&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
{{Mathanalysis-stub}}&lt;/div&gt;</summary>
		<author><name>en&gt;BattyBot</name></author>
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