Covariant derivative summation convention help

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SUMMARY

The discussion focuses on the covariant derivative of a vector \( V \) with respect to a component \( Z_k \), specifically the expression \( \frac{\partial V_i Z_i}{\partial Z_k} = Z_i \frac{\partial V_i}{\partial Z_k} + V_i \frac{\partial Z_i}{\partial Z_k} = Z_i \frac{\partial V_i}{\partial Z_k} + V_i \Gamma_{mi} Z_m \). Participants clarify that indices \( m \) and \( i \) in \( V_i \Gamma_{mi} Z_m \) are dummy indices, which can be renamed without altering the equation's meaning. This understanding is crucial for manipulating tensor equations in differential geometry.

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Mathematicsresear
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Homework Statement


Assume that you want to the derivative of a vector V with respect to a component Zk, the derivative is then ∂ViZi/∂Zk=Zi∂Vi/∂Zk+ViZi/∂Zk = Zi∂Vi/∂Zk+ViΓmikZm Now why is it that I can change m to i and i to j in ViΓmikZm?
 
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Mathematicsresear said:

Homework Statement


Assume that you want to the derivative of a vector V with respect to a component Zk, the derivative is then ∂ViZi/∂Zk=Zi∂Vi/∂Zk+ViZi/∂Zk = Zi∂Vi/∂Zk+ViΓmikZm Now why is it that I can change m to i and i to j in ViΓmikZm?
What do you mean by "I can change m to i and i to j"?
 
What are the boldface ##Z_m##s. Are they supposed to be coordinate basis vectors? If so, and you are really expressing the covariant derivative in this way, then there should be ##\mathbf{Z_k}## also, so that there are dyadic products of coordinate basis vectors. The gradient of a vector is a 2nd order tensor.
 
Mathematicsresear said:
1. Now why is it that I can change m to i and i to j in ViΓmikZm?

Because in that expression "m" is a dummy index and so is "i". The name of a dummy index can be changed without changing the meaning of the equation
 

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