Einstein summation convention proof

In summary, using the Einstein summation convention, it was proven that A\bulletB\timesC = C\bulletA\timesB by showing that e_{ijk}=e_{jki}.
  • #1
tigger88
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Homework Statement


Using the Einstein summation convention, prove:

A[tex]\bullet[/tex]B[tex]\times[/tex]C = C[tex]\bullet[/tex]A[tex]\times[/tex]B


Homework Equations





The Attempt at a Solution


I tried to follow an example from my notes, but I don't entirely understand it. Would it be possible to find out if what I've done (below) is correct, or where I went wrong?

(B[tex]\times[/tex]C)[tex]_{i}[/tex] = [tex]\epsilon[/tex][tex]_{ijk}[/tex]B[tex]_{j}[/tex]C[tex]_{k}[/tex]

(A[tex]\bullet[/tex]B[tex]\times[/tex]C)[tex]_{i}[/tex] = [tex]\epsilon[/tex][tex]_{ijk}[/tex]A[tex]_{i}[/tex]B[tex]_{j}[/tex]C[tex]_{k}[/tex]

= [tex]\epsilon[/tex][tex]_{kij}[/tex]A[tex]_{i}[/tex]B[tex]_{j}[/tex]C[tex]_{k}[/tex]

=C[tex]\bullet[/tex]A[tex]\times[/tex]B

Thanks!
PS. I'm not very familiar with Latex and couldn't get the symbols to line up properly.. sorry! They should all be subscripts.
 
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  • #2
I think that's about right. The thing is just to show that e_{ijk}=e_{jki}, right?
 

1. What is the Einstein summation convention?

The Einstein summation convention is a mathematical notation used in tensor calculus and relativity theory. It allows for a more compact and simplified representation of equations involving repeated indices.

2. How does the Einstein summation convention simplify proofs?

The convention eliminates the need to explicitly write out summation signs and indices, making equations easier to read and understand. It also reduces the number of terms in a proof, making it more concise.

3. What are the basic rules of the Einstein summation convention?

The basic rules of the convention are as follows:

  • Repeated indices in a single term are to be summed over.
  • Each index can only appear twice in an equation, once as a subscript and once as a superscript.
  • Indices that are not repeated are considered to be dummy indices, and the equation is to be summed over all possible values of these indices.

4. How is the Einstein summation convention used in proofs?

The convention is used to simplify and compactly represent equations involving tensors and repeated indices. It is commonly used in proofs related to relativity theory, as well as in other branches of mathematics and physics.

5. Are there any limitations to the Einstein summation convention?

While the convention is a useful tool for simplifying equations, it does have some limitations. It can only be applied to equations involving tensors and repeated indices, and it may not be suitable for more complex proofs or equations involving multiple variables and operations.

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