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	<title>Du Bois singularity - Revision history</title>
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	<updated>2026-08-03T09:51:28Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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		<id>https://en.formulasearchengine.com/w/index.php?title=Du_Bois_singularity&amp;diff=24230&amp;oldid=prev</id>
		<title>89.244.108.152: added &lt;math&gt; instead of &#039;&#039;foo&#039;&#039;</title>
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		<updated>2013-01-07T07:37:50Z</updated>

		<summary type="html">&lt;p&gt;added &amp;lt;math&amp;gt; instead of &amp;#039;&amp;#039;foo&amp;#039;&amp;#039;&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;{{about|an extension of the theory of the [[Lebesgue integral]] to [[manifold]]s|numerical method|geometric integrator}}&lt;br /&gt;
In the [[mathematics|mathematical]] fields of [[differential geometry]] and [[geometric measure theory]], &amp;#039;&amp;#039;&amp;#039;homological integration&amp;#039;&amp;#039;&amp;#039; or &amp;#039;&amp;#039;&amp;#039;geometric integration&amp;#039;&amp;#039;&amp;#039; is a method for extending the notion of the [[integral]] to [[manifold]]s.  Rather than functions or [[differential form]]s, the integral is defined over [[current (mathematics)|currents]] on a manifold.&lt;br /&gt;
&lt;br /&gt;
The theory is &amp;quot;homological&amp;quot; because currents themselves are defined by duality with differential forms.  To wit, the space &amp;#039;&amp;#039;D&amp;#039;&amp;#039;&amp;lt;sup&amp;gt;&amp;#039;&amp;#039;k&amp;#039;&amp;#039;&amp;lt;/sup&amp;gt; of &amp;#039;&amp;#039;k&amp;#039;&amp;#039;-currents on a manifold &amp;#039;&amp;#039;M&amp;#039;&amp;#039; is defined as the [[dual space]], in the sense of [[distribution (mathematics)|distributions]], of the space of &amp;#039;&amp;#039;k&amp;#039;&amp;#039;-forms Ω&amp;lt;sup&amp;gt;&amp;#039;&amp;#039;k&amp;#039;&amp;#039;&amp;lt;/sup&amp;gt; on &amp;#039;&amp;#039;M&amp;#039;&amp;#039;.  Thus there is a pairing between &amp;#039;&amp;#039;k&amp;#039;&amp;#039;-currents &amp;#039;&amp;#039;T&amp;#039;&amp;#039; and &amp;#039;&amp;#039;k&amp;#039;&amp;#039;-forms α, denoted here by&lt;br /&gt;
:&amp;lt;math&amp;gt;\langle T, \alpha\rangle.&amp;lt;/math&amp;gt;&lt;br /&gt;
Under this duality pairing, the [[exterior derivative]] &lt;br /&gt;
:&amp;lt;math&amp;gt;d : \Omega^{k-1} \to \Omega^k&amp;lt;/math&amp;gt;&lt;br /&gt;
goes over to a [[boundary operator]]&lt;br /&gt;
:&amp;lt;math&amp;gt;\partial : D^k \to D^{k-1} &amp;lt;/math&amp;gt;&lt;br /&gt;
defined by&lt;br /&gt;
:&amp;lt;math&amp;gt;\langle\partial T,\alpha\rangle = \langle T, d\alpha\rangle&amp;lt;/math&amp;gt;&lt;br /&gt;
for all α&amp;amp;nbsp;∈&amp;amp;nbsp;Ω&amp;lt;sup&amp;gt;&amp;#039;&amp;#039;k&amp;#039;&amp;#039;&amp;lt;/sup&amp;gt;.  This is a homological rather than [[cohomology theory|cohomological]] construction.&lt;br /&gt;
&lt;br /&gt;
==References==&lt;br /&gt;
* {{citation&lt;br /&gt;
| last = Federer&lt;br /&gt;
| first = Herbert&lt;br /&gt;
| authorlink = Herbert Federer&lt;br /&gt;
| title = Geometric measure theory&lt;br /&gt;
| publisher = Springer-Verlag New York Inc.&lt;br /&gt;
| location = New York&lt;br /&gt;
| year = 1969&lt;br /&gt;
| pages = xiv+676&lt;br /&gt;
| isbn = 978-3-540-60656-7&lt;br /&gt;
| id= {{MathSciNet|id=0257325}}&lt;br /&gt;
| series = series Die Grundlehren der mathematischen Wissenschaften&lt;br /&gt;
| volume = 153 }}&lt;br /&gt;
* {{citation&lt;br /&gt;
|first=H.&lt;br /&gt;
|last=Whitney&lt;br /&gt;
|author-link=Hassler Whitney&lt;br /&gt;
|title=Geometric Integration Theory&lt;br /&gt;
|series=Princeton Mathematical Series&lt;br /&gt;
|volume=21&lt;br /&gt;
|publisher=[[Princeton University Press]] and [[Oxford University Press]]&lt;br /&gt;
|place=Princeton, NJ and London&lt;br /&gt;
|year=1957&lt;br /&gt;
|pages= XV+387&lt;br /&gt;
|mr=0087148&lt;br /&gt;
|zbl=0083.28204&lt;br /&gt;
}}.&lt;br /&gt;
&lt;br /&gt;
[[Category:Definitions of mathematical integration]]&lt;br /&gt;
[[Category:Measure theory]]&lt;br /&gt;
&lt;br /&gt;
&lt;br /&gt;
{{geometry-stub}}&lt;/div&gt;</summary>
		<author><name>89.244.108.152</name></author>
	</entry>
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