Semicolon notation in component of covariant derivative

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Discussion Overview

The discussion revolves around the use of semicolon notation in the context of covariant derivatives, specifically whether it serves as a compact notation for components or if it can be expanded in a certain way. The scope includes theoretical aspects of tensor notation and covariant derivatives.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants inquire about the meaning of the semicolon in tensor notation, questioning if it indicates a covariant derivative or serves as a compact notation for components.
  • One participant asserts that the semicolon can indeed represent the covariant derivative, providing the equation $$S^\alpha{}_{\beta\gamma;\delta} = \nabla_\delta \, S^{\alpha}{}_{\beta\gamma}$$ as an example.
  • Another participant suggests that any tensor can be expressed as a sum of its components multiplied by basis vectors and co-vectors, indicating that the covariant derivative of a tensor remains a tensor of higher rank.
  • There is a request for clarification on how to type equations, with a participant sharing that LaTeX is used for this purpose on the forum.

Areas of Agreement / Disagreement

The discussion contains multiple viewpoints regarding the interpretation of the semicolon notation, and no consensus is reached on its usage. Participants express uncertainty and seek clarification on the topic.

Contextual Notes

Some assumptions about the familiarity with tensor notation and the properties of covariant derivatives may not be explicitly stated, which could affect understanding.

berlinspeed
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TL;DR
The use of semicolon notation as covariant derivative
Can someone clarify the use of semicolon in
245677

I know that semicolon can mean covariant derivative, here is it being used in the same way (is
245678
expandable?) Or is
245679
a compact notation solely for the components of
245680
?
 
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If you're familiar with index or abstract index notation

$$S^\alpha{}_{\beta\gamma;\delta} = \nabla_\delta \, S^{\alpha}{}_{\beta\gamma}$$
 
berlinspeed said:
Can someone clarify the use of semicolon in
View attachment 245677
I know that semicolon can mean covariant derivative, here is it being used in the same way (is View attachment 245678 expandable?) Or isView attachment 245679 a compact notation solely for the components ofView attachment 245680?
Not sure what your confusion is. Any tensor can be written as the sum of each of its components in some basis multiplied by the outer product of the respective basis vectors and co-vectors. Since the covariant derivative of a tensor is still a tensor (but one rank higher), it can also be written this way. Does that clear anything up for you?
 
pervect said:
If you're familiar with index or abstract index notation

$$S^\alpha{}_{\beta\gamma;\delta} = \nabla_\delta \, S^{\alpha}{}_{\beta\gamma}$$
Hello thank you, can you tell me what did you use to type your equations? I'm new to this site and trying to find a good way to generate equations. Much appreciated.
 
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