Skew Symmetry: Inner Product of Rows & Determinant

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Discussion Overview

The discussion revolves around the properties of skew symmetric matrices, particularly focusing on the inner product of their rows and the implications for determinants. Participants explore the relationship between skew symmetry, the determinant function, and the Levi-Civita symbol, with a mix of theoretical and conceptual inquiries.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether the inner product of the rows of a skew symmetric matrix equals zero, linking this to the properties of determinants.
  • Another participant explains that the determinant is an alternating form and will vanish if two columns are identical, referencing its definition using the Levi-Civita symbol.
  • A participant expresses confusion about the Levi-Civita symbols and their connection to skew anti-symmetry.
  • One participant seeks clarification on why the determinant function is skew anti-symmetric, relating it to the definition involving permutations and the homomorphism from the symmetric group.
  • A participant provides a link to a resource on the basis-free definition of the determinant, which is not aligned with the original inquiry.
  • The same participant reiterates their request for help, indicating that the provided resource did not address their specific problem.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the properties of skew symmetric matrices and determinants. There is no consensus on the reasons behind the skew anti-symmetry of the determinant function, and confusion persists about the role of the Levi-Civita symbol.

Contextual Notes

Participants have not fully resolved the connections between skew symmetry, determinants, and the Levi-Civita symbol. There are indications of missing assumptions and definitions that may affect the clarity of the discussion.

Tenshou
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I am entranced. I mean There are so many thing which seem to deal with skew symmetry, like the skew anti-symmetric matrices of Electromagnetic 4-tensor, I have this thing, a question. And it is stated as: " if you take the inner product of the rows of a skew symmetric matrix would it be equal to 0" because I remember hearing, or reading some where that the determinant of a matrix is its diagonals
 
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No but the determinant itself is an alternating form meaning the determinant of a matrix with two identical columns will vanish; you might have seen in say relativity textbooks the determinant is defined using the levi-civita symbol so the above property of the determinant is immediately apparent when cast in such form (in LA books like Friedberg you would see the determinant characterized as the unique n-linear alternating map that sends the identity matrix to 1).
 
That actually helps! But, the levi-civita symbols are a little confusing @_@ I mean just in general I don't understand why that is a reason for skew anti-symmetry
 
Why what is a reason?
 
D: maybe I asked the question wrong, I was asking, or trying to ask why does the determinant function hold to be skew anti-symmetric n-linear function phi from one vector space to another. In the book the determinant function is defined as ## \Delta = \sum_{\sigma} \epsilon_{\sigma}\left(\sigma\Phi\right) ## and ##\forall\sigma\in S_{n}## which is a set of permutations and epsilon is a homomorphism from ##S_{n}## to the multiplicative set {1,-1} and when ##\epsilon_{\sigma}## is even (when ##\epsilon_{\sigma}## is odd respectively) < that right there is similar to the levi-civita but I don't understand why it makes it skew anti-symmetric, is it because phi is skew symmetric?
 
D: but I am not looking for a basis free definition, thank you for the resource but that hasn't settled this problem D:
 
bump D:
please help?
 

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