Difference between revisions of "Hodge star"

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m (No. The subject is way too esoteric. But "cotangent" does not refer to high-school level trigonometry.)
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{{math-a}}
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The '''Hodge star operator''' is a function important in [[differential geometry]] and [[topology]].<ref>[http://mathworld.wolfram.com/HodgeStar.html MathWorld]</ref>
  
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Let <math>M</math> be a [[Riemannian manifold]] in <math>n</math> dimensions with [[metric]] <math>g</math>. The '''Hodge star''' operator is a [[linear]] [[operator]] from i-[[differential form]]s to (n-i)-differential forms
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==References==
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<references/>
  
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<math>
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[[Category:Mathematics]]
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*: \Omega^i(T^*M) \rightarrow \Omega^{n-i}(T^*M)
 
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</math>
 
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defined as follows: Let <math>\phi_1,...,\phi_n</math> be a local orthonormal [[coframe]] (i.e., a collection of locally defined 1-forms which are [[orthonormal]] with respect to the induced metric on the <!--Don't wikilink this unless you know what you are doing-->cotangent space). Then we define
 
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<math>
 
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*\phi_1\wedge\cdots\wedge\phi_i = \pm \phi_{i+1}\wedge\cdots\wedge\phi_n
 
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</math>
 
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where the plus or minus is chosen so that
 
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<math>\phi_1\wedge\cdots\wedge\phi_i\wedge *(\phi_1\wedge\cdots\wedge\phi_i)</math>
 
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is the [[volume]] form on <math>M</math>. To define the Hodge star operator for general forms, we simply extend the above definition by [[linearity]].
 
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==Example==
 
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Give <math>R^2</math> the standard metric so that <math>dx, dy</math> is a coframe. Then the volume form is <math>dx\wedge dy</math>. Thus,
 
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<math>
 
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*dx = dy
 
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</math>
 
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and
 
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<math>
 
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*dy = -dx
 
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</math>
 
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and in general
 
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<math>
 
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* fdx + gdy = fdy - gdx
 
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</math>
 
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[[Category:Calculus]]
 

Latest revision as of 14:00, July 13, 2016

The Hodge star operator is a function important in differential geometry and topology.[1]

References