Hodge duality and some properties

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Discussion Overview

The discussion revolves around Hodge duality, particularly its application to complex functions and partial derivatives. Participants explore the implications of Hodge duality in different contexts, including Euclidean and Lorentzian manifolds, and the treatment of complex variables.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a formula for Hodge duality and inquires about its application to the imaginary unit "i" and partial derivatives of complex functions.
  • Another participant questions the appropriateness of the forum category, noting that the provided formula may not be correct for Lorentzian-signature manifolds but is valid for Euclidean signature.
  • It is suggested that on a complex manifold, the simultaneous application of Hodge dual and complex conjugate is typically of interest.
  • A participant requests clarification regarding the Hodge dual of the expression involving the partial derivative of a complex function.
  • There is a discussion about the nature of the function α, with one participant asserting it is a complex function, while another identifies it as a 0-form.
  • A later reply proposes a specific expression involving the Hodge dual of a partial derivative, but it remains unclear if this is correct or accepted by others.

Areas of Agreement / Disagreement

Participants express differing views on the correctness of the Hodge duality formula in various contexts, particularly regarding signature types and the treatment of complex variables. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

There are limitations in the discussion regarding the assumptions about the signature of the manifold and the definitions of forms, particularly in the context of complex functions and their derivatives.

PhyAmateur
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So we know that [Hodge duality](http://en.wikipedia.org/wiki/Hodge_dual) works this way

$$⋆(dx^i_1 \wedge ... \wedge dx^i_p)= \frac{1}{(n-p)!} \epsilon^{i_1..i_p}_{i_{p+1}..i_n} dx^{i_{p+1} } \wedge dx^{i_n}$$

where p represents the p in p-form and n is the dimensional number.

My question is: How does hodge duality work on the imaginary number "i" on one hand and on partial derivative like $$\partial_x\alpha$$ let us say on the other where $$\alpha$$ is a complex function.
 
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Why is this in GR rather than in the differential geometry forum? The formula you've written is not correct on Lorentzian-signature manifolds.

However, in Euclidean signature, this is correct:

PhyAmateur said:
$$⋆(dx^i_1 \wedge ... \wedge dx^i_p)= \frac{1}{(n-p)!} \epsilon^{i_1..i_p}_{i_{p+1}..i_n} dx^{i_{p+1} } \wedge dx^{i_n}$$

where p represents the p in p-form and n is the dimensional number.

And it means exactly the same thing if you make all of your variables complex.

The catch is that on a complex manifold, one is usually more interested in taking the Hodge dual and the complex conjugate simultaneously.
 
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Thanks. I would appreciate if we could move this to the other section or if you could guide me so that I can move it. On the other hand, I want to ask you to please elaborate on your answer, because this answer doesn't make it clear to me if we have for example $$\star{(i\partial _x \alpha)}$$ it is also the partial differential that is worrying me. @Ben Niehoff
 
What is ##\alpha##?
 
Any complex function, I mentioned that in the given. @Ben Niehoff
 
So, a function is a 0-form. What's the Hodge dual of a 0-form?
 
$$-1/3 (i \partial _x \alpha) dx \wedge dy \wedge dz?$$ @Ben Niehoff
 

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