Duality Pairing and Functionals

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Discussion Overview

The discussion revolves around the concept of duality pairing in relation to functionals, particularly in the context of mathematical definitions and applications. Participants explore the meaning of duality pairing, its implications for functionals, and the interpretation of gradients of functionals.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asks for clarification on the meaning of duality pairing in connection with functionals, referencing a specific mathematical expression.
  • Another participant requests better formatting for clarity, indicating that the original post is difficult to understand.
  • A participant shares a definition of duality pairing from a book, highlighting two different representations of duality pairing and questioning the interpretation of the gradient of a functional.
  • There is a challenge regarding the clarity of the original question, suggesting that lack of effort in formulating the question may deter responses.
  • One participant asserts that DF(u) is a functional and explains the relationship between gradients and inner products in Euclidean space.
  • Another participant clarifies that the inner product results in a real number, prompting further inquiry into the implications of this interpretation.

Areas of Agreement / Disagreement

Participants express differing views on the nature of DF(u) and its classification as a functional or a value. The discussion remains unresolved with multiple interpretations presented.

Contextual Notes

There are limitations in the clarity of the original mathematical expression and the definitions provided, which may affect participants' understanding and interpretations.

maros522
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Hello all,

does anybody know what means duality pairing in connection with functional. For example limE\rightarrow0\frac{\partial}{\partialE}F(u+Ev)=<DF(u),v>. Where F is functional F:K\rightarrowR.

Thank You for answers.
 
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please write with proper formatting .. it is not possible to guess what you mean ...
 
Hello, I find definition of duality pairing in book
http://books.google.cz/books?id=zTV...onepage&q=duality pairing functional&f=false"
The part of interest is as jpg in attachments - dualitypairing1.jpg
But in book Contact problem in elasticity from Oden and Kikuchi is definition like in dualitypairing2.jpg.
In dualitypairing2.jpg is used as functional gradient of functional F at u. I don't understand how it is meaned. If g is part of V' we write g(v)=<g,v>: in this the g is functional. But in dualitypairing2.jpg is DF(u), which is gradient of F at u. This DF(u) is still functional or is it a value.
 

Attachments

  • dualitypairing1.jpg
    dualitypairing1.jpg
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  • dualitypairing2.jpg
    dualitypairing2.jpg
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Last edited by a moderator:
nobody will bother replying to you if you don't make any effort to clarify what u r asking.
 
DF(u) is a functional. Think of it this way: the gradient of a function takes a point and gives you back a vector. The inner product on euclidean space allows you to transform that vector into a function.
 
Thank you for posting messages.
Nirax: the question was "This DF(u) is still functional or is it a value?" I forget to add ?.
Zhentil: The inner product on euclidean space is dot product of two vectors. So the result will be real number. How do you think it?
 

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