Evaluating if a Vector is a Tensor

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SUMMARY

The discussion evaluates whether the four-component object \(\left( \frac{1}{A^0},\frac{1}{A^1},\frac{1}{A^2},\frac{1}{A^3}\right)\) qualifies as a tensor under the Einstein summation convention. The transformation rules for contravariant and covariant vectors are applied to analyze the components of the object. The conclusion hinges on whether the transformed object adheres to the tensor transformation rules. A hint suggests that a transformation can be found that sets one of the coefficients of \(A'\) to zero, indicating a potential path to resolving the inquiry.

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  • Familiarity with contravariant and covariant vectors.
  • Knowledge of transformation rules in tensor calculus.
  • Basic concepts of linear algebra related to vector spaces.
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Homework Statement


Problem as stated: Consider a vector A^a. Is the four-component object \left( \frac{1}{A^0},\frac{1}{A^1},\frac{1}{A^2},\frac{1}{A^3}\right) a tensor?


Homework Equations


Roman indices run from 0 to 3. Einstein summation convention is used.
Tensors of rank 1 (vectors) transform as
Contravariant vectors: A^a = \frac{\partial x^a}{\partial x ' ^b}A'^b
Covariant vectors: A_a = \frac{\partial x'^b}{\partial x^a}A'_b


The Attempt at a Solution


I use the above mentioned transformation rules for each of the individual components getting:
\left( \frac{1}{A^0},\frac{1}{A^1},\frac{1}{A^2},\frac{1}{A^3}\right) = \left(\frac{1}{\frac{\partial x^0}{\partial x'^b}A'^b},\frac{1}{\frac{\partial x^1}{\partial x'^b}A'^b},\frac{1}{\frac{\partial x^2}{\partial x'^b}A'^b},\frac{1}{\frac{\partial x^3}{\partial x'^b}A'^b}\right)

What I wanted was to transform the object to another frame and either arriving at a transformed object according to the above mentioned rules (confirming it is a tensor) or being unable to fit it into one of the rules above (disproving the object to be a tensor).

I am currently stuck with how to proceed.
 
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Presumably all of those Aa are non-zero, and hence 1/Aa is bounded.

Hint: Certainly you can find a transformation that sets one of the coefficients of A' to zero.
 

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